Multiplying ones will always give you palindromic numbers.

For those who are unaware, a palindromic number is simply a number that is the same backwards as forwards, for example, 23432.

So, if you calculate 1 × 1, we get 1. Ok, that’s a bit of a lazy palindrome, let’s move on.

11 × 11 = 121,

111 × 111 = 12321,

1111 × 1111 = 1234321,

and keep going. If you multiply 111111111 × 111111111 you get 12345678987654321.

Furthermore, it is not necessary to have the same number of ones in the two numbers you are multiplying. For example 11 × 1111 = 12221 and

111111 × 1111 = 123444321.