Mathematical magic

Puzzles, situation puzzles and recreational mathematics.

situation puzzles and recreational mathematics. Neuron juice

Neuron juice.

The important thing is not to stop questioning. (Albert Einstein.)


Write on paper the number 12345679 (Attention, missing 8 )

Ask a friend to tell you a number from 1 to 9.

Mentally multiply it by 9 writes the result under number 12345679 and ask your friend to multiply the two numbers .

You will be amazed of the result.



Put on the table a sealed envelope , a paper and a pen.

Ask a friend to write on paper any three-digit number , for example 528.

Ask him to write this issue with inverted numbers in our example 825 and subtract the least senior , 825-528 = 297 .

and finally to add the digits of the number obtained , 2 + 7 + 9 = 18 .

Then open the envelope and pulls out a paper put before closing with " The number obtained is 18 "

Which as you know?
The result is always 18 , only a precaution , the initial number can not be palindromic , by making the subtraction would result 0.



Put one on top of the table and asked to write this time a 4-digit number , eg 2536

Below that number to enter another with the same digits but in a different order , for example 3265 .

You subtract the least senior , 3265-2536 = 729 and adding up the digits of the number obtained , 7 + 2 + 9 = 18 .

If the result is a two-digit number that join each 1 + 8 = 9.

Opens the envelope and pulls out the paper where you wrote " The number obtained is 9 "



By Felipe Márquez.

Think about the number of times a week that you would like to go dining out

Multiply by 2 and add 5

Multiply by 50

Depending on your birthday :
- If you spent your birthday Throw in 1755
- If you have not spent sum 1754

Subtract the year of your birth including 4 digits.

You obtained a 3-digit number :
- The first is the number of times you thought at first
- The secondis your age!