A number theory problem by sudoku subbu

$1^{2} = 1$

$11^{2} = 121$

$111^{2} = 12321$

thus , a sequence is observed . This is only true till 9 ones

$111111111^{2} = 12345678987654321$

By splitting up the second number, we get the sum 111111111 x 100000000 + 111111111 x 10000000 + ... + 111111111 x 1. By using long multiplication in which the 111111111 is stacked skewly, the digits of the sum become 1, 1+1, 1+1+1, ... , 1+1 and 1 which is in other words 12345678987654321.

Write a solution. It have a trick to solve 1x1=1 11x11=121
111x111=12321 1111x1111=1234321 U have to see how many 1's are there suppose 5 ones then write counting from 1 to 5 than reverse 4 to 1 . this how u will get the answer 111111111^2=12345678987654321