求未知数问题（7岁以上）
Missing number problems (age 7+)
利用数字规律、位值观念和更复杂的方法，解决包括求未知数在内的加减法问题。
Solve addition and subtraction problems including missing-number problems, using number facts, place value, and more complex methods
学习证据 / Evidence
- 解决一道求未知数问题，例如 245 + ? = 380
- 根据数字情况选择合适的方法（心算、笔算或两者结合）
- 解决结合三位数加减法的多步问题
- Solve a missing-number problem such as 245 + ? = 380
- Choose an appropriate method (mental, written, or combination) based on the numbers
- Solve multi-step problems combining addition and subtraction of three-digit numbers
评估问题 / Assessment
{{name}}能否通过仔细思考等式表达的意思，算出带有隐藏数字的算式——如“? − 38 = 24”或“53 + ? = 91”这样的题目？
Can {{name}} work out sums with a hidden number — like '? − 38 = 24' or '53 + ? = 91' — by thinking carefully about what the equation is asking?