.svg){kind=logo}
MathXplosion
The Magic Number
6174 is a very mysterious number. In 1949 the mathematician D. R. Kaprekar from India, devised a process now known as Kaprekar's operation. First choose a four digit number where the digits are not all the same. Then rearrange the digits to get the largest and smallest numbers these digits can make. Finally, subtract the smallest number from the largest to get a new number, and carry on repeating the operation for each new number. You always reach 6174: a constant.