Squaring numbers. FAST.

Do you remember about your friends keep on mentioning about algebric formulas? If not, here is a few:


(X+Y)(X+Y)=X(X)+Y(Y)+2XY
(X-Y)(X-Y)=X(X)+Y(Y)-2XY
X(X)-Y(Y)=(X-Y)(X+Y)
...
There are many more! However, today, we will be only focusing on one. The third one stated over there. Now, let us go into the secrets of squaring mathematical numbers.
Your number X, is going to be squared. Let's say if X is 68. Then let us make Y = 2. As 68+2 = 70, it will be easier to calculate as it can be split into 7 * 10. In the formula
X(X)-Y(Y)=(X-Y)(X+Y), we can change it to
X(X)=(X-Y)(X+Y)+Y(Y) where X is our number that is going to be squared. So, with our example, 68, let's test this out.
68(68)=(68-2)(68+2)+2(2)
=68(68)=(66)(70)+4
=68(68)=4620+4
=68(68)=4624
Now, let's check! Correct! Don't you see how efficient it was? Also, for Y, try and pick the lowest value for it but still when you add or subtract Y to/from X, we get a number divisible by 10.
  
Credit: https://www.youtube.com/watch?v=_FoONg5Meyc