--- title: "Fluent addition and subtraction (age 9+)" description: "Fluently add and subtract whole numbers with more than four digits using the standard columnar algorithm" canonical: https://lightmysky.com/learn/mathematics/fluent-addition-and-subtraction-age-9-mt_Yw1_4Nfsql source: https://lightmysky.com/learn/mathematics/fluent-addition-and-subtraction-age-9-mt_Yw1_4Nfsql.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`. # Fluent addition and subtraction (age 9+) Fluently add and subtract whole numbers with more than four digits using the standard columnar algorithm Subject: Mathematics · Area: Addition & Subtraction · Ages 9 to 10 Page: https://lightmysky.com/learn/mathematics/fluent-addition-and-subtraction-age-9-mt_Yw1_4Nfsql ## Ready when they can - Calculate 34,567 + 28,945 using columnar addition - Calculate 500,000 − 234,178 using columnar subtraction with multiple exchanges - Add three five-digit numbers in a single column layout ## Lesson: Adding and subtracting big numbers You already know how to add and subtract with columns. Now you'll use the exact same steps on numbers with five, six, or more digits. Line up the digits by place value, then work one column at a time from right to left. *(drawing: The ones column of 47,658 + 35,786 says 8 + 6 = 14. The 4 stays in the column, and the 1 ten carries to the next column on the left. Tap the dots to count them.)* **Example.** Add 47,658 + 35,786. Line up the places and start at the ones. Ones: 8 + 6 = 14, write 4 and carry 1. Tens: 5 + 8 + 1 = 14, write 4 and carry 1. Hundreds: 6 + 7 + 1 = 14, write 4 and carry 1. Thousands: 7 + 5 + 1 = 13, write 3 and carry 1. Ten thousands: 4 + 3 + 1 = 8. The answer is 83,444. **Example.** Subtract 300,000 − 152,647. The ones digit is 0, and so is every digit up to the 3. Exchange from the 3: it becomes 2, each 0 it passes becomes 9, and the ones become 10. This exchange is also called borrowing. Now subtract each column: 10 − 7 = 3, 9 − 4 = 5, 9 − 6 = 3, 9 − 2 = 7, 9 − 5 = 4 and 2 − 1 = 1. The answer is 147,353. You can add three or more numbers in one layout. Line them all up and add each column from the right. A column total from 20 to 29 has 2 tens, so write its ones digit and carry 2 to the next column. For example, 9 + 9 + 8 = 26, so write 6 and carry 2. Estimate first by rounding, so a slip stands out. **Recap.** The column method works on any size number: line up the place values, then carry or borrow one column at a time. ## Practice 17 questions on this page, each with its working shown. ## Needs first - [Fluent addition and subtraction](https://lightmysky.com/learn/mathematics/fluent-addition-and-subtraction-mt_3e_PQxwC12) - [Adding and subtracting (age 8+)](https://lightmysky.com/learn/mathematics/adding-and-subtracting-age-8-mt_mpS-JK_p_m) ## Opens up - [Adding and subtracting (age 9+)](https://lightmysky.com/learn/mathematics/adding-and-subtracting-age-9-mt_-F_Lv_apzH) - [Addition and subtraction strategies (age 10+)](https://lightmysky.com/learn/mathematics/addition-and-subtraction-strategies-age-10-mt_JH_6RpNWjr)