Approximation and quick calculation: Evaluate 21 + (3.7 × 2.9) and select the closest option.

Introduction / Context:Small decimal multiplications can be handled mentally by rounding to one decimal place and then adjusting slightly. Here, the choices are far apart, so a near-exact evaluation is straightforward and safe.

Given Data / Assumptions:

• Expression: 21 + 3.7 * 2.9
• Choose the closest option to the true value.

Concept / Approach:Approximate 3.7 * 2.9 as 3.7 * 3.0 − 3.7 * 0.1. Then add 21. Because the product is under 11 and options jump by 5 or more, closeness is guaranteed.

Step-by-Step Solution:

Verification / Alternative check:Compute exactly: 3.7 * 2.9 = (37/10)*(29/10) = 1073/100 = 10.73; add 21 → 31.73. Same conclusion.

Why Other Options Are Wrong:

• 74, 70: Too large for a small decimal multiplication added to 21.
• 27: Below the base 21 + 6; not possible.
• None of these: 32 is clearly the closest.

Common Pitfalls:Rounding 2.9 to 3 and forgetting to subtract 0.37, which slightly overstates the result but still keeps 32 as the nearest choice.

Final Answer:32