find square of a number between 50 and 60

find square of a number between 50 and 60
for example......
56^2=3136
57^2=3249
58^2=3364

there is a 2 steps trick to get the ans
1) add the digit at the units place to 25 and write the sum
2) then calculate the square of units place digit and write it

eg in case of 56^2
we have 25+6=31
and square of 6 is 36
hence the result is 3136