Mathematics
Addition & Subtraction
Procedural
7–8 yrs
Mental addition and subtraction (age 7+)
心算加减法（7岁以上）
Description
Mentally add and subtract a three-digit number and ones
Mastery Evidence
- Calculate 345 + 7 mentally
- Calculate 462 − 5 mentally
- Explain that only the ones digit changes (unless bridging through a ten)
Assessment Prompt
Can your child work out '436 + 7' or '521 − 8' in their head — keeping the hundreds and tens unchanged while adjusting just the ones?
