20.992 − 24.97% of 220.02 − ? = 131.13

Concept

In an approximation (simplification) problem, replace every awkward decimal with the nearest convenient whole number, then evaluate with simple arithmetic. Two handy roundings apply here: a decimal just below a whole number is squared at that whole number, and a percentage close to 25% is treated as one-fourth (÷4).

Application

1. Round each term: 20.99 ≈ 21, 24.97% ≈ 25% (= 1/4), 220.02 ≈ 220, and the right side 131.13 ≈ 131.

2. Evaluate the square: 212 = 441.

3. Evaluate the percentage: 25% of 220 = 220 ÷ 4 = 55.

4. Substitute into the expression: 441 − 55 − ? = 131, which simplifies to 386 − ? = 131.

5. Solve for the blank: ? = 386 − 131 = 255.

Cross-check

Using exact values: 20.992 = 440.58, and 24.97% of 220.02 = 54.94, so 440.58 − 54.94 − 131.13 = 254.51, which rounds to 255 — confirming the rounded result.