This is an extremely important idea. It comes up all the time in algebra, so the fact that you've asked it now will benefit you a great deal later.
7* 63 =
7(60 + 3) Notice what you have done. You have broken up 63 into 60 + 3. Is 63 not the same thing as 60 + 3?
7(63) = 7 * ( 60 + 3) = 7*60 + 7*3 = 420 + 21 In algebra you will be taught to leave this as the answer. 420 + 21 = 441
441 <<<<< answer.