Answer:
D. (43 +60) +40
Step-by-step explanation:
The purpose of changing the grouping in addition problems is to simplify the mental effort required as much as possible. This will generally mean grouping ...
- "complementary" numbers,
- numbers with the same number of leading or trailing zeros,
- numbers with the same sign, and
- fractions with the same denominator.
Analysis
A. Numbers ending in 0 are already grouped; no change is needed.
B. Fractions with the same denominator are already grouped; no change is needed.
C. Numbers with the same (negative) sign are already grouped; no change is needed.
D. Numbers ending in zero could be grouped to make addition easier:
43 +(60 +40) . . . . regrouping would be useful
We also note that in A and D, the sum of numbers ending in zero is 100, so these numbers are "complements" of each other. This is another reason for grouping them together.
