M a t h e m a t i c a l j o k e s
Two students-mathematicians, having birthdays on the same day, wished each other many happy returns on this day. One of them said:
- You’ll have such birthday only in 11 years.
The other answered him:
- Okay, but you’ll have such birthday only in 96 years.
Both of them were satisfied with each other. How old were they on this day ?
S o l u t i o n. One of them was
25, and other 24. Why?
25=52,
the next square is 62=36, i.e. in 11 years.
24=4!,
the next factorial is 5!=120, i.e. in 96 years.
A pupil divides 28 by 7 and receives as a result 13. His teacher
asks him:
- How did you receive this result ?
- First I divide 8 by 7 and receive 1. Now 1 x 7 = 7 and I
write:
The teacher asks him to check the result by
multiplication. The pupil answers:
- I execute 13 x 7 by the steps:
1) 1 x 7 = 7,
2) 3 x 7 = 21,
3) 7 + 21 = 28.
The teacher asks him to check the result by addition. The pupil
answers:
- First I add 3 seven times and receive 21, then I add 1 seven
times and receive 28.
A teacher of English was ill and a teacher of
mathematics replaced him. He began to compose a table of irregular verbs:
Then he said:
- Okay, I mark this form as x . Then it’s possible
to compose the proportion:
Why do we hear a clatter of train wheels ?
Answer: Wheel has a form of a circle. An area of a circle is equal to p r 2, so this square clatters.
Answer: Physicist thinks that 1 kilobyte = 1000 bytes, and programmer thinks that 1 kilometer = 1024 meters.
At a geometry lesson a teacher asks to represent the shortest distance between the two points A and B on a blackboard:
- Johnny, who taught you this ?
- My father, he is a taxi driver
Sequence
Continue the sequence: z, o, t, … .
S o l u t i o n . As z = zero, o = one, t = two, the continued sequence is:
z, o, t, t, f, f, s, s, e, n, t, …
At the parents’ meeting
At the parents’ meeting a teacher of mathematics
complains of his pupils to their parents:
- Your children are very dull. Today I explained them a new theorem. I
explained once, they didn’t understand. I explained
once again, they didn’t understand. I explained the third time, I understood myself, but they still didn’t understand.
Proof
At a geometry lesson a teacher asks to draw an
isosceles triangle. One of the pupils draws it. The teacher:
- Now prove that this triangle is really isosceles.
- Sir, I give you a word of a gentleman.
Daily time-table
One absent-minded professor composed a daily time-table
and showed it to his assistant. The assistant looked it through and said:
- Very well, but your day consists of 25 hours.
- What a pity! Now I must wake up one hour earlier.
New about limits
At a mathematics exam a professor asks a student
to calculate the limit:
The professor is surprised:
- What is it ? Why ?
The student answers:
- You explained at your lecture that
and I have used this example.
The shortest telegrams in a history
German mathematician Dirichlet was very taciturn. When his son was born, he sent to his father-in-law the following telegram: “2 +1 = 3”. Maybe it’s one of the shortest telegrams in the history. But the shortest telegram conversation ever was between Oscar Wilde and his publisher regarding his new book. O. Wilde wired the single character “?” and received from his publisher the reply: “!”.
New in chemistry
At a chemistry exam a professor asks a student:
- Tell me please, how to get sulphur.
The student answers:
- Let’s take hydrogen sulphide and warm it up. Hydrogen
evaporates and sulphur remains.
- Very well. I put you an “excellent” and warm it up. A
“good” and a “fair” evaporate and a “poor” remains.
Euclid’s wisdom
Euclid was asked:
- What do you want: two whole apples or four halves ?
- Four halves, of course.
- Why ? It’s the same, isn’t it ?
- No, it isn’t. Choosing two whole apples, I can not see
if they are maggoty or aren’t.
Leibniz’s bust
Friends of Leibniz gave him as a present his bust,
made by famous sculptor, on his birthday. Leibniz stared at the
bust for a long time and then said:
- So, this is a face, which I shave every day.
Einstein and telephone
One woman asked Einstein to remember her telephone
number: 361-343.
Einstein answered:
- It’s very easy. 19 squared and 7 cubed.
Einstein at school
A teacher of algebra said to Einstein’s father:
- I have never met a duller child.
An honest sergeant
A sergeant teaches young soldiers:
- Water boils at 90 degrees.
One of the soldiers retorts:
- I’m sorry, sir. But I know that water boils at 100 degrees.
- Okay, I’ll check, - the sergeant answered.
The next day the sergeant says:
- You were right. Water boils at 100 degrees, I mixed up
with a right angle.
New method of fast calculus
Two Englishmen are going by train. A conversation
isn’t getting on. The train passes a meadow, on which a herd of cows pastures.
One of the passengers says:
- 1356.
The other man is surprised, but gives no answer. In some time
the train passes another pasture. The first passenger says:
- 1693.
His neighbor brakes and asks:
- Sir, our train moves at speed 60 miles per hour. How can you
count so quickly ?
- Oh, sir, it’s very simple! First I count a quantity of legs
in a herd and then I divide this number by four.
Study and money
“Dear John!
I send you 50 dollars, as you asked. By the way remember please that the number 50 is written with one zero, but not with two.”
About terrestrial gravity
A sergeant explains to young soldiers a gist of Earth gravity:
- If to throw a stone upwards, then it drops to the ground. This means, that the terrestrial gravity effects it.
One of the soldiers asks:
- What if it drops into water?
- It doesn’t refer to us. This problem is considered by fleet.
At exam
An examiner asks a student:
- What is your name ?
- John Smith, sir.
- Why do you smile ?
- I’m satisfied with my answer for the first question.
An excellent work
A teacher returns a pupil his work:
- Not a single mistake was made! Johnny, tell me honestly, did anybody help your father ?
Valid reason
A teacher asks a pupil:
- Why does your father make home tasks for you every day ?
- Because my mother is always busy.
Study, sonny
- Dad, I’m expelled from the college.
- Don’t weep, I’ll buy you a new college.
School’s news
- Were you asked at school today ?
- Yes, I was.
- What about ?
- Why are you always absent at the parents’ meetings ?
Business-like conversation
- Uncle Bill, I need to tell you something.
- Well, but tell briefly and clearly.
- 100 dollars, please.
General disaster
Two boys went to a doctor.
- What do you complain about ? – the doctor asks.
- I swallowed 50 cents. – one of the
boys answered.
- And why do you weep ? – the doctor asks
the other boy.
- This is my money.
Fast calculation
A teacher asks:
- Tommy, find please a sum of these two numbers.
- But I didn’t lose it, sir.
About inertia
- Johnny, give an example of inertia.
- A car has stopped, but a driver is
going farther.
-------
- What is an inertia force ?
- A ball is flying to a window and it’s
impossible to catch it.
An essence answer
At an arithmetic lesson a teacher asks:
- How many will it remain, if to subtract 1
from 100 ?
- Two zeros.
Fast solution
A teacher of mathematics writes an equation on a
blackboard and calls a pupil:
- Billy, find x please.
- I have found, here it is! – the pupil answers
and shows to x with a finger.
Working week
- A cow gives 20 liters of milk a day. How many
liters of a milk is it possible to get for a week ?
- But we don’t know, how many days a week a cow
works.
Physics news
As it’s known, the famous Albert Einstein tried to solve the problem of time-space unity during last twenty years of his life and didn’t solve it. However this problem was solved recently by sergeant Brown. He drew up a platoon of soldiers and ordered them to dig a ditch from fence till dinner hour.
New in geometry
- How is the biggest side in a right-angled
triangle called ?
As all the pupils keep silent the
teacher begins to help:
- Hy-po-…
- Hippopotamus !
New definition of fraction
- If to take one tomato and to cut it by 4 parts, then each lobule is one fourth part of a tomato. Now do you understand what is a fraction ?
- Yes, it is a part of salad !
Eureka !
- … And then Archimedes jumped out of a bath
and exclaimed:
“Eureka!” – a pupil reads.
- What is “eureka” ? – a teacher asks.
- “Eureka” means “he found”.
- Well. Now tell me please, what
Archimedes found in a bath.
- I think, he found soap.
Twice guilty
A pupil tells his comrade:
- Yesterday my father punished me twice.
- Why ?
- The first time he punished me when I
showed him a diary and the second time, when the father understood that
this was
his old diary.
Beautiful present
- Uncle Bill, thank you very much for the
trumpet, that you gave me as a present.
- Do you like the trumpet, Teddy ?
- Of course! Mother pays 3 dollars to me
not to play in the day-time, and my father pays 5 dollars to me
not to play in the evening.
At exam
An examiner:
- Why do you wink at me ?
A student:
- Professor, I signal you that my knowledge is
coming to an end.
-------
An examiner:
- What do you want: one difficult question or
two easy ones ?
- One difficult, professor.
- Okay, tell me please, where the first people
appeared.
- In London, sir.
- Why in London ?
- I’m sorry, professor, but this is
already the second question.
Wonders of technical progress
A sergeant bought an electronic watch. A boy
comes up and asks him:
- Tell me please, what the time is.
- Twelve, divided by thirty one.
- What does it mean ?
- Go away, boy. I have been dividing myself for
half a day already.
Foreseeing monkey
Two monkeys are dismantling an atom bomb.
- I’m afraid it will blust. – says one of them.
- Don’t worry, I have another one.
Business-like conversation
- Uncle Bill, I need to tell you something.
- Well, but tell briefly and clearly.
- 100 dollars, please.
Foreseeing cow
A crow flies and sees that a cow climbs up a
birch. The crow asks:
- What are you doing?
- I want to eat apples. – the cow answers.
- Are you fool ? Do you know that apples don’t
grow on birches ?
- Never mind, I have taken them with me.
If logic is week …
One man asks his friend:
- John, tell me please, haw many cakes you can
eat on an empty stomach.
- Five, I think.
- This is wrong. If you eat only one cake, then
the others won’t be on an empty stomach.
- This is very interesting puzzle. I’ll tell it
my wife.
At home John asks his wife:
- Tell me please my darling, haw many cakes you
can eat on an empty stomach.
- Six, maybe seven.
- Oh, what a pity! If you said “five” I could
play a practical joke at you.
New decimal numeration
- Tell me please, Billy, how many zeros are
written in one million.
- Six, sir.
- Well, and how many zeros are written in
half-million ?
- Three, sir.
Revenge
A pupil runs to a policeman:
- Go with me, but quickly!
- What has happened ?
- Our teacher has parked his car in a forbidden
place.
What a speed !
A policeman fined a woman who drove at the speed
100 kilometers per hour! She was very surprised:
- It’s impossible! I have never heard that so
many kilometers could be in one hour!
-------
A policeman stops a driver-disturber:
- Why are you going at the speed 120 kilometers
per hour ?
- Hour ? – the driver is surprised. – I drive
only 15 minutes!
-------
Two friends go by car at the speed 160
kilometers per hour.
- What a speed! And what will happen to us, if a wheel flies off ?
- Don’t worry! I have a spare wheel.
On entrance exams in military academy
An examiner:
- Captain, solving this equation, you have
received that this sine is equal to 4!
Don’t you know that it’s impossible ?
- Sir, a value of sine can achieve 4 in
wartime!
-------
- Tell me please, major, what an ellipse is.
- Ellipse is a
circle, inscribed in a square with the sides 2 and 4.
Resourceful pupil
- Teddy, imagine please that you look northward. What is behind you ?
- My back, sir.
Gentlemen bought a camel. A seller said to him that the camel knew the three commands: “Phew!” – go, “Hi!” – run, “Amen!” – stop. Gentleman said: “Phew!” and the camel went, then he said : “Hi!” and the camel ran. Suddenly the gentleman saw that the camel ran toward a precipice, but he forgot how to stop the camel. Understanding that his death was inevitable, he began to pray and said at the end of the prayer: “Amen!”. The camel stopped on the precipice edge. The gentleman wiped sweat from the forehead and said: “Phew!”.
Three
friends went to a sage and asked to judge them. They bought together 18
lambs. The first man paid a half of the whole cost, the second – a
third and the last – 1 / 9 of the whole cost. They wanted to divide the
lambs, but so that all the lambs were alive. The sage said to them: “I
can judge you, but I want to get one of the lambs as a reward”. The men
agreed. Then the sage gave 9 lambs to the first man, 6 lambs – to the
second man, 2 lambs – to the last man andtook 1 lamb for himself. As a
result all of them were satisfied. What was a cause of the situation ?
S o l u t i o n. A cause of this situation was that these three men paid:
of the whole cost, i.e. they paid only for 17 lambs, but not for 18.
Thus, a seller of the lambs actually presented 1 lamb to the sage.
He got the loss, because he didn’t know to count.
In the middle of the XX century Russia was a country, where all people knew mathematics perfectly. In 1965 one newspaper wrote: ”Do you know that a cost of 0.25 liter of vodka, raised to the power, equal to a cost of 0.5 liter of vodka is the number p with accuracy of three first digits ?”. You can convince in this fact yourself, if to consider that a bottle of 0.25 liter of vodka cost 1.49 ruble, and a bottle of 0.5 liter of vodka cost 2.87 ruble in 1965. Check!
Achilles
runs after a turtle. Achilles’ velocity is 10 times more than turtle’s
velocity. First moment the distance between them is equal to100 m.
Achilles runs these 100 m, a turtle creeps 10 m. Achilles runs this 10
m, a turtle creeps 1 m. Achilles runs 1 m, a turtle creeps 0.1 m.
Achilles runs 0.1 m, a turtle creeps 0.01 m, and so on. Hence, Achilles
will never catch up a turtle ! Explain, please this paradox, known as
Zenonian one.
S o l u t i o n. A cause of this paradox consists in dividing continuous time into
parts. We consider smaller and smaller time intervals and receive
the paradox as a result. Actually, Achilles will outrun a turtle,
of course! Assume that Achilles runs 100 m in 10 seconds, then
in next 10 seconds he will run else 100 m, and a turtle will creep
this time only 20 m.
Once
a group of 8 guests was taking seats around a big table in a restaurant
during a long time. An owner watched this and then said that he agreed
to feed them gratis on condition that they would take seats newly every
day. How long will he feed them gratis on this condition ?
S o l u t i o n. This is a classic problem of theory of combinations. Each combination
of guests around a table is a permutation, so the number of all
possible permutations is equal to
8! = 40320 days ≈ 110 years.
Thus, the owner agrees to feed them gratis for 110 years!.
Two friends meet. One of them says:
- Yesterday I was in a circus and saw a trained boa. His length is 8 meters from a head to a tail and 9 meters from a
tail to a head.
- It’s impossible!
- Why? Don’t you know that from Monday to Sunday there are 7 days, and from Sunday to Monday there is only 1 day.
London. Midnight. It’s raining. Can one believe in a weather forecast, that in 72 hours a weather
in London will be sunny ?
S o l u t i o n. No, one can’t, because in 72 a midnight will be again, and a sunny
weather in a middle latitude may be only in the daytime.
- You are welcome!
A thief was afraid at the beginning, but then he calmed down, because the dog made nothing. Capturing jewels and money he wanted to go away and asked the parrot at the end:
- Well, don’t you know other words, foolish bird ?
The parrot answered:
- Bite him, boy!
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