Mathematics
Addition & Subtraction
Procedural
9–10 yrs
Fluent addition and subtraction (age 9+)
加减法流利运算（9岁以上）
Description
Fluently add and subtract whole numbers with more than four digits using the standard columnar algorithm
Mastery Evidence
- Calculate 34,567 + 28,945 using columnar addition
- Calculate 500,000 − 234,178 using columnar subtraction with multiple exchanges
- Add three five-digit numbers in a single column layout
Assessment Prompt
Can your child accurately add or subtract large numbers — like '23,846 + 14,579' — using the column method, carrying and borrowing correctly however many columns it takes?
