用估算检验计算结果

运用估算来检验计算结果，并能根据题目情境判断合适的精确度。

Use estimation to check answers to calculations and determine, in the context of a problem, an appropriate degree of accuracy

学习证据 / Evidence

• 通过将487×23按500×20来估算，并用这个结果检查计算出的答案。
• 判断在特定情境下，精确答案和估算哪个更合适。
• 通过快速心算估算，发现不合理的答案。

• Estimate 487 × 23 by rounding to 500 × 20 and use this to check a calculated answer
• Determine whether an exact answer or an estimate is more appropriate in a given context
• Spot an unreasonable answer by comparing with a quick mental estimate

评估问题 / Assessment

在{{name}}算出较大的乘法或除法之前，能否先粗略估计答案应该是多少，并检查最终答案是否大致合理？

Before {{name}} works out a large multiplication or division, can they estimate what the answer should be roughly — and then check whether their final answer is in the right ballpark?