sabrina used a calcutator and started adding the whole numbers in order 1+2+3+4+5+..... what is the last number she would add that would get the sum on her calculator over 1000?

Try it yourself. You'll be surprised that it won't take very long to add up to 1,000.

To find the sum of the numbers from 1 to "n":
(1+n)(n/2)=sum
1001=(n^2+1)/2
2002=n^2+1
2001=n^2
n=44.7.....
So, 45 is the last number she would add.