--- title: "Adding and subtracting" description: "Add and subtract one-digit and two-digit numbers to 20, including zero" canonical: https://lightmysky.com/learn/mathematics/adding-and-subtracting-mt_mr_Vk7FGzK source: https://lightmysky.com/learn/mathematics/adding-and-subtracting-mt_mr_Vk7FGzK.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`. # Adding and subtracting Add and subtract one-digit and two-digit numbers to 20, including zero Subject: Mathematics · Area: Addition & Subtraction · Ages 5 to 6 Page: https://lightmysky.com/learn/mathematics/adding-and-subtracting-mt_mr_Vk7FGzK ## Ready when they can - Calculate 14 + 5 = 19 - Calculate 17 – 3 = 14 - Add or subtract 0 and explain the result stays the same ## Lesson: Adding and Subtracting to 20 Adding puts numbers together. The total grows. Subtracting takes some away. The total shrinks. You already know number bonds. Use them to add fast. *(drawing: Hop forward 5 from 14 to land on 19. Hop back 3 from 17 to land on 14.)* **Example.** Zoe has 8 crayons. She takes away 0 crayons. She still has 8 crayons. Zero never changes the number. **Tip.** Start with the bigger number. Count up or down from there. Number bonds help you add fast. **Recap.** Adding grows a number, subtracting shrinks it, and zero never changes it. ## Practice 20 questions on this page, each with its working shown. ## Needs first - [Number bonds](https://lightmysky.com/learn/mathematics/number-bonds-mt_s2mfRBoTal) ## Opens up - [Mental addition and subtraction (age 6+)](https://lightmysky.com/learn/mathematics/mental-addition-and-subtraction-age-6-mt_AKAtWEwpcj) - [Early Word Problems](https://lightmysky.com/learn/mathematics/early-word-problems-mt_VAWV_l7J0D)