anon for this
(x+0.5)*(x+0.5) = x^2 +.5x + .5x +.25 = x^2 + x +.25.
=> 4.5 * 4.5 = 4^2 + 4 + .25 = 20.25
I agree that this will work but I found that my students had a hard time performing more than two mathematical operations mentally. (x+0.5)*(x+0.5) = x^2 +.5x + .5x +.25 reduces to three terms x^2 + x +.25 , by (x – 2)*(x + 2), the two middle terms cancel out so there are only two terms left, x^2 – 4.
If you (or your daughter) have no issue with this consider yourself gifted.