---
title: "Adding and subtracting (age 8+)"
description: "Add and subtract numbers with up to four digits using formal written methods of columnar addition and subtraction"
canonical: https://lightmysky.com/learn/mathematics/adding-and-subtracting-age-8-mt_mpS-JK_p_m
source: https://lightmysky.com/learn/mathematics/adding-and-subtracting-age-8-mt_mpS-JK_p_m.md
retrieved: 2026-10-19
---

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# Adding and subtracting (age 8+)

Add and subtract numbers with up to four digits using formal written methods of columnar addition and subtraction

Subject: Mathematics · Area: Addition & Subtraction · Ages 8 to 9
Page: https://lightmysky.com/learn/mathematics/adding-and-subtracting-age-8-mt_mpS-JK_p_m

## Ready when they can

- Set out and solve a columnar addition with up to four-digit numbers
- Set out and solve a columnar subtraction with exchange across multiple columns
- Check the answer using estimation or inverse operations

## Lesson: Adding and subtracting big numbers

You already know how to carry and exchange with smaller numbers. Now you will do the same with thousands, hundreds, tens and ones. Line up the digits by place value, ones on the right, and work from right to left. When a column adds up to 10 or more, write the ones digit and carry 1 to the next column on the left.

*(drawing: Add 3,842 + 1,765 from right to left. The tens make 10 and the hundreds make 16, so write the ones digit and carry 1 each time. The answer is 5,607.)*

In subtraction, take the bottom digit away from the top digit in each column. If the top digit is smaller, exchange 1 from the next column on the left for 10. If that column is 0, go one more column left and exchange there first.

**Example.** Subtract 4,301 − 2,658. Ones: 1 is less than 8, and the tens digit is 0. So exchange 1 hundred for 10 tens, then 1 ten for 10 ones. Ones: 11 − 8 = 3. Tens: 9 − 5 = 4. Hundreds: 2 is less than 6, so exchange 1 thousand for 10 hundreds: 12 − 6 = 6. Thousands: 3 − 2 = 1. The answer is 1,643.

Estimate by rounding each number, then adding or subtracting. The exact answer should be close. Use the opposite operation for an exact check: if 3,842 + 1,765 = 5,607, subtract 1,765 from 5,607 to get 3,842. To check 4,301 - 2,658 = 1,643, add 1,643 + 2,658 to get 4,301.

**Recap.** Line up numbers by place value, carry or exchange when a column doesn't fit, and always check your answer.

## Practice

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

## Needs first

- [Place value of each digit](https://lightmysky.com/learn/mathematics/place-value-of-each-digit-mt_jY7uf0Cb7o)
- [Adding and subtracting (age 7+)](https://lightmysky.com/learn/mathematics/adding-and-subtracting-age-7-mt_SrrsLiJkr3)

## Opens up

- [Two-step addition and subtraction problems](https://lightmysky.com/learn/mathematics/two-step-addition-and-subtraction-problems-mt_CDa5AVakLE)
- [Fluent addition and subtraction (age 9+)](https://lightmysky.com/learn/mathematics/fluent-addition-and-subtraction-age-9-mt_Yw1_4Nfsql)