Question

Select the proper placement for parentheses to speed up the addition for the expression 4 + 6 + 5 A. (4 + 6) + 5 B. (5 + 6) + 4 C. 4 + (6 + 5) D. (5 + 4) + 6

Answer 1

I believe it should be A, because it's easier to add 10 to anything rather than 11 or 9.  

Answer 2

I think it's A. Because 6+4 is 10 +5 it would be 15