Find the Missing Number
Work out the missing number in each equation, then match it to its answer. The blank moves around — sometimes it's an addend, sometimes the number you take away, sometimes the total — so you get to think it through every way. Tap an equation, then tap the number that makes it true, and watch the pair link. Aligned to Common Core 1.OA.D.8 — finding the unknown whole number in an addition or subtraction equation, in any position.
Work out the missing number in each equation, then match it to its answer. The blank moves around — sometimes it's an addend, sometimes the number you take away, sometimes the total — so you get to think it through every way. Tap an equation, then tap the number that makes it true, and watch the pair link. Aligned to Common Core 1.OA.D.8 — finding the unknown whole number in an addition or subtraction equation, in any position.
About this activity
Children solve cards like ? + 4 = 9, 8 + ? = 11, ? − 3 = 4, and 10 − ? = 6, then tap the equation and the number that completes it to link the pair. It's a free, interactive Grade 1 math activity that runs right in the browser, with nothing to install and no account.
The big idea is that the unknown can sit anywhere — a missing addend, a missing number to subtract, the starting number, or the total — so a child has to think the relationship through each time rather than always "adding to find the answer." Sometimes the blank is the total (5 + 4 = ?) and sometimes it is hidden inside the problem (? − 4 = 1), which builds true fact-family flexibility.
It is aligned to Common Core 1.OA.D.8 — finding the unknown whole number in an addition or subtraction equation, with the unknown in any position. No timer, no score — just calm, playful practice.
What's inside this activity
- Designed for Grade 1 learners (ages about 6–7)
- Common Core strand: Operations & Algebraic Thinking
- Aligned to Common Core standard 1.OA.D.8
How to play
Read an equation card with a blank, like ? + 7 = 10, and work out the missing number.
Tap the equation, then tap the number that makes it true, and watch the pair link.
Match both pairs in the round — there is no timer and no score, so take your time.
What your child practices
- Find a missing addend, a missing subtrahend, a missing minuend, or the total
- Use the relationship between addition and subtraction to solve for the unknown
- Count on or count back to find a missing part
- Match each equation to the number that makes it true
Learning goals
Find the unknown number in an addition or subtraction equation, in any position — the focus of Common Core 1.OA.D.8
Understand how addition and subtraction undo each other
Build flexible thinking with fact families instead of one fixed procedure
Frequently asked questions
- What does the Find the Missing Number activity teach?
- Find the Missing Number is a free interactive activity for Grade 1, focused on Operations & Algebraic Thinking. Children play it right in the browser — no printing, login, or setup required.
- Is Find the Missing Number free to use?
- Yes. Find the Missing Number is completely free, with no signup and no paywall, on any tablet, laptop, or classroom whiteboard.
- Which ages is this activity for?
- It is designed for Grade 1 (Operations & Algebraic Thinking) and works well for whole-class, small-group, or independent practice.