easy problem!

[rachelcapt]

can someone / anyone tell me the trick to solve

501^2 - 400^2

Beginning to feel a little stupid now :blushing:

[shmoe]

It's a difference of two squares, a^2-b^2=(a+b)(a-b).

[Tide]

can someone / anyone tell me the trick to solve

501^2 - 400^2

Beginning to feel a little stupid now :blushing:

Incidentally, you are not solving anything. You are simplifying a numerical expression. "Solve" generally means you are obtaining the value of one or more unknown quantities.

[rachelcapt]

Thank you both
(seems so obvious now you've helped me simplify it!)