lichess.org
Donate

Magic number :)

That is extremely interesting. If n is any number which is divisible by neither 2,3, or 5, can you prove that there is a multiple of n whose decimal expansion can be written with 1's only?

A few examples:
n=7 : 15 873×n=111111
n=13 : 8 547 008 547×n=1111111111111
@Passionate_Player said in #6:
> 111 * 111 = 12321
> 1111 * 1111 = 1234321
> and so on
It’s basically a normal maths though Nothing is magic in math it’s just logic
Like 1+2+3+4+5=15
2+3+4+5+6=20
3+4+5+6+7=25
As you can see the numbers are adding with 5. You may think this is magic first but if you understand the logic that we are taking numbers 1 more than the number before it
<Comment deleted by user>

This topic has been archived and can no longer be replied to.