Mathematics
Addition & Subtraction
Procedural
9–10 yrs
Mental addition and subtraction (age 9+)
心算加减法（9岁以上）
Description
Add and subtract numbers mentally with increasingly large numbers, using place-value knowledge and derived facts
Mastery Evidence
- Mentally calculate 45,000 + 8,000
- Mentally subtract 3,200 from 10,000 by counting up
- Use near-doubles: 2,500 + 2,600 = 5,100
Assessment Prompt
Can your child work out something like '4,700 − 1,300' in their head using what they know about place value — without needing to write it all out?
