111…… 1155…… 56 is a perfect square

111…… 1155…… 56 is a perfect square

111 '` 155' ` 56 (n 1, n-1, 5)
=111```1555```5+1
=111```1*(100```0+5)+1
=333```3*333```5+1
=(333```34-1)(333```34+1)+1
=333```34^2-1+1
=333```34^2