Number 6174

The number is ‘6174’ and ‘495’ is called ‘Kaprekar’s constant’ as this was discovered by an Indian mathematician D. R. Kaprekar.

What it does?

Step one: Take any 4 digit number let’s say ‘6354’

Step two: sort it in descending and assign it to ‘a’
So, a = 6543

Step three: sort it in ascending and assign it to ‘b’
So, b = 3456

Step four: (a-b) and assign to a
So, a = 3087

Repeat:
a = 8730
b = 0378
(a-b) = 8352
Repeat:
a = 8532
b = 2358
(a-b) = 6174
Repeat:
a = 7641
b = 1467
(a-b) = 6174


To learn more facts about interesting numbers
Visit numberphile: http://www.youtube.com/user/numberphile