乘除法心算
Mental multiplication and division
利用位值、已知事实和推导事实进行乘除法心算，包括乘以0和1、除以1，以及把三个数相乘。
Use place value, known and derived facts to multiply and divide mentally, including multiplying by 0 and 1, dividing by 1, and multiplying together three numbers
学习证据 / Evidence
- 利用位值进行心算，例如 40 × 6 = 240。
- 能解释为什么任何数乘0都等于0，任何数乘1都等于它本身。
- 心算三个数相乘时，先选择一组好算的数，例如 2 × 7 × 5 = 2 × 5 × 7 = 70。
- Calculate 40 × 6 = 240 mentally using place value
- Explain why any number × 0 = 0 and any number × 1 = the number itself
- Multiply three numbers mentally by choosing a useful pair first (e.g. 2 × 7 × 5 = 2 × 5 × 7 = 70)
评估问题 / Assessment
{{name}}能利用已经知道的知识，而不是从零开始一步步计算，马上在脑子里算出像“6 × 0”“1 × 35”“100 ÷ 100”这样的题目吗？
Can {{name}} work out things like '6 × 0', '1 × 35', or '100 ÷ 100' instantly in their head — using what they know rather than working everything out from scratch?