---
title: "Missing number problems (age 7+)"
description: "Solve addition and subtraction problems including missing-number problems, using number facts, place value, and more complex methods"
canonical: https://lightmysky.com/learn/mathematics/missing-number-problems-age-7-mt_XuHmIn2xje
source: https://lightmysky.com/learn/mathematics/missing-number-problems-age-7-mt_XuHmIn2xje.md
retrieved: 2026-10-19
---

> **Agent view.** This is the Markdown twin of the page, for tools and assistants.
> When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md
> API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md
> Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt
> Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json
> Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`.

# Missing number problems (age 7+)

Solve addition and subtraction problems including missing-number problems, using number facts, place value, and more complex methods

Subject: Mathematics · Area: Addition & Subtraction · Ages 7 to 8
Page: https://lightmysky.com/learn/mathematics/missing-number-problems-age-7-mt_XuHmIn2xje

## Ready when they can

- Solve a missing-number problem such as 245 + ? = 380
- Choose an appropriate method (mental, written, or combination) based on the numbers
- Solve multi-step problems combining addition and subtraction of three-digit numbers

## Lesson: Finding the missing number

Some sums have a secret number, shown as a box or a question mark. Your job is to find what is hiding. The trick is simple: use the numbers you already know to work out the missing one.

*(drawing: The hop from 53 to 91 is the missing number. Count the gap: 91 − 53 = 38.)*

**Example.** Zara sees this sum: 245 + ? = 380. She knows the start and the end, so she flips it into a subtraction: 380 − 245 = 135. The missing number is 135.

**Tip.** Addition and subtraction are opposites. If a missing number is in a plus sum, turn it into a minus sum. If it is in a minus sum, turn it into a plus sum.

**Example.** Ben has 375 stickers. He gives away 120, then he gets 45 more. First subtract: 375 − 120 = 255. Then add: 255 + 45 = 300. Ben now has 300 stickers.

**Recap.** To find a missing number, swap the plus and minus around, then work out the gap.

## Practice

17 questions on this page, each with its working shown.

## Needs first

- [Adding and subtracting (age 7+)](https://lightmysky.com/learn/mathematics/adding-and-subtracting-age-7-mt_SrrsLiJkr3)
- [Two-Step Word Problems](https://lightmysky.com/learn/mathematics/two-step-word-problems-mt_yTWxkzzoOZ)

## Opens up

- [Two-step addition and subtraction problems](https://lightmysky.com/learn/mathematics/two-step-addition-and-subtraction-problems-mt_CDa5AVakLE)
- [Multi-Step Problem Solving](https://lightmysky.com/learn/mathematics/multi-step-problem-solving-mt_RKeheOL9uo)