What is the sum of all whole numbers from 1 to 10?
Answer and explanation
Correct answer: C.
- Step 1: Pair the first and last numbers: each pair sums to 11. Step 2. There are 5 pairs, so the sum is 10 × 11 ÷ 2 = 55. **Answer: . Why not the others:** is what you get if you use n²/2. is what you get if you forget to halve. is what you get if you stop at 9.
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