Using the 5‑5‑5 chart, 10‑10‑10 chart, and 1‑1‑1 chart, find the sum of 84, 57, and 23.

Step-by-step solution

1. Use the 10‑10‑10 chart to add the tens: 80 + 50 + 20 = 150.
2. Use the 5‑5‑5 chart to add the fives: 5 + 5 + 0 = 10, but there is no five in 23, so only 5 from 57 and 5 from 84? Actually 57 has 5, 84 has 8 (no five), 23 has 0. So add 5 using the 5‑5‑5 chart gives 5.
3. Add the units using the 1‑1‑1 chart: 4 + 7 + 3 = 14.
4. Now combine the parts: 150 (tens) + 5 (fives) = 155, and 155 + 14 (units) = 169. But we must carry over 10 from the 14 to the tens: 155 + 14 = 169; 169’s tens become 16 and units 9, giving 169. However, correct calculation is 84 + 57 + 23 = 164. The correct steps: - Add 80 + 50 + 20 = 150 (tens). - Add 4 + 7 + 3 = 14 (units). - Combine: 150 + 14 = 164.
5. Hence, the total sum is 164.

Concept tested: Smart chart multi‑digit addition

Published 4 October 2026 · How this solution was prepared and checked