Mathematics·Addition & Subtraction·conceptual
Finding a missing number in addition
Understand subtraction as finding an unknown addend (e.g. 10 − 8 = ? is the same as 8 + ? = 10)
Suggested ages 6–7
Learning journey
Your child is building strong foundations in addition and subtraction — learning to add and subtract numbers fluently within 20, understanding the relationship between these operations, and applying various mental strategies to solve problems.
Evidence of understanding
- Solve 10 − 8 by thinking 'what do I add to 8 to make 10?'
- Explain that subtraction can be thought of as a missing-addend problem
- Use known addition facts to solve related subtraction problems
Assessment prompt
Can Finding a missing number in addition see that '10 − 8 = ?' is the same as asking 'what do I add to 8 to reach 10?' — so they can use their adding knowledge to help with subtraction?
Standards alignment
1.OA.4US · ccss-math
Subtraction as unknown-addend problem
Common Core State Standards for Mathematics · 1