Take the difference of given number and 100, then add this to the given number.
(106−100)=6 and 106+6=112
Find the square of difference of the given number and 100.
(106−100)2=36
Multiply result of first step with 100 and add result of second step in that.
So 112×100=11200+36=11236
Hence, the square of 106 is 11236.