Number Bonds to 20
Free printable number bonds to 20 worksheets with answers. Find the missing part that makes 20 using the part-part-whole model. Great for building addition and subtraction fluency. Play online or print the PDF.
Fill in the missing number so the two parts make the whole — you'll see a ✓ when it's right.
Explore the Elementary Math & Number Sense Sequence
A structured progression following the Concrete-Pictorial-Abstract (CPA) framework — from part-whole number bonds to inverse operations, multi-digit arithmetic, and algebraic functions.
Number Bonds
Part-part-whole foundation to 10, 20 & 100
Learn How to Play, Solve & Teach Number Bonds to 20
Elementary Math Mastery: A Guide to Number Bonds, Fact Families & Number Pyramids
A complete parent and teacher guide to mastering early mental math. Learn how number bonds, fact families, and number pyramids build deep conceptual numeracy from kindergarten through 4th grade.
What Are Number Bonds? A Simple Guide for Parents and Teachers
Number bonds show how a number splits into two parts — the part-part-whole idea behind all early addition and subtraction. Learn what they are, why they matter, and generate free printable number bonds worksheets to 10, 20, and 100.
Frequently asked questions
What is a number bond?+
A number bond shows how a number breaks into two parts — two 'parts' that combine to make a 'whole'. It's drawn as a part-part-whole diagram: the whole on top, connected to its two parts below. For example, 10 splits into 6 and 4.
Why are number bonds important?+
They build the part-part-whole understanding that underpins addition and subtraction. A child who knows the bonds of 10 can add and subtract within 10 instantly, and the same idea powers mental math strategies like making ten.
What ages are number bonds for?+
Bonds to 10 suit Kindergarten and Grade 1 (about ages 5–6), bonds to 20 fit Grades 1–2, and bonds to 100 work well for Grades 2–3 as place value develops.
Do the worksheets include answers?+
Yes. Every downloaded PDF has a full answer key on the next page, and you can reveal answers on screen. On screen you also get instant ✓/✗ feedback as you type.
Are the number bonds worksheets free?+
Yes. Generate unlimited worksheets and play, print, or download them for free — no signup.