I've been doing about 2-3 NS tests a day. I've figured out all sorts of cool problems, but this one beats me every time.
If 125 = x^2 - y^2 and x > y are positive integers then x = ___________________
I figured this one out by thinking 15^2 - 10^2 = 125, but I did this rather arbitrarily... How do you do harder versions of this quickly and accurately?
These ones are weird because they have multiple answers sometimes.
For these I do difference of squares that are one apart(only works when x^2 - y^2 = odd number)-find two consecutive integers that add to the number. in this case its 63 and 62. Did the answer key say 15 or 63?
2-3 tests a day is a solid amount. I was doing that before district and regionals and that's when my scores really rose. I've finished all the tests from '90-'05 and am going through dr. numsen tests now. Some of the problems on the thursday tests (they are the hardest tests yet he ranks them medium? ) are impossible
) are impossible 
