Finding a missing number in addition
Understand subtraction as finding an unknown addend (e.g. 10 − 8 = ? is the same as 8 + ? = 10)
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“Can your child 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?”
Full guide and materials
- Activity. Understand subtraction as finding an unknown addend (e.g. 10 − 8 = ? is the same as 8 + ? = 10)
What to notice. 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
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Can your child 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?
Understand subtraction as finding an unknown addend (e.g. 10 − 8 = ? is the same as 8 + ? = 10)
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Learning resources
Reviewed external links that reinforce this concept. They do not replace Gakuva’s teaching approach.
Topmarks · Practice link — not the full lesson
Hit the Button · Number Bonds
Find the missing partner in a bond—the same skill as a missing addend. Choose Number Bonds and an appropriate total.
Free · no login · ads · timed play
Review and open practice
Save a Number Bonds screenshot and a parent note of two missing-number equations solved (for example 7 + ___ = 10).
Opening this link does not save learning or assess mastery.
Open practice (new tab)Source, access and review notes
Find the missing partner in a bond—the same skill as a missing addend. Choose Number Bonds and an appropriate total.
Save a Number Bonds screenshot and a parent note of two missing-number equations solved (for example 7 + ___ = 10).
Free · no login · ads · timed play
Unknown — link only
Visnos · Practice link — not the full lesson
Addition & Subtraction Facts
Supplemental visual for relating a whole and parts when one addend is unknown. Cover one part and ask what is missing.
Free · no login · no ads observed
Review and open practice
Save a screenshot and a parent note of a missing-addend question answered from the model.
Opening this link does not save learning or assess mastery.
Open practice (new tab)Source, access and review notes
Supplemental visual for relating a whole and parts when one addend is unknown. Cover one part and ask what is missing.
Save a screenshot and a parent note of a missing-addend question answered from the model.
Free · no login · no ads observed
Unknown — link only
Check 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
“Can your child 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?”
Curriculum record
- Type
- Conceptual
- Subject
- Mathematics
- Domain
- Addition & Subtraction
- Age range
- Ages 6–7
Standards