🔢Math Standard
Number Bonds Worksheet
Fill in the missing number in each number bond - sometimes a part, sometimes the whole.
2nd Grade 10 min
✓ Answer key
2nd Grade · Math
2nd Grade Number Bonds Worksheets
Number bonds show how a number splits into two parts — the foundation of addition and subtraction fact fluency. These free printable 2nd grade number bonds worksheets use the classic circle diagram to practice composing and decomposing numbers to 20, including finding the missing part when one part is unknown. Every worksheet includes a printable answer key and easy, standard, and challenge versions for differentiation.
Reviewed by ClassReady Editorial Team Last updated August 2026
Before this skill
- Counting to 20
- Addition facts to 10
- Understanding part-part-whole
Common mistakes to watch for
- Adding the two parts instead of finding the missing part
- Writing a bond that doesn't add up to the whole
- Swapping the parts and calling it a different bond
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Frequently Asked Questions
What are number bonds in 2nd grade?
A number bond shows a whole and its parts, like a circle with the whole on top and two parts below. For the whole 7, the parts could be 3 and 4.
Why are number bonds useful?
They make the part-part-whole relationship visible, which is exactly what students need for mental addition, subtraction, and later algebra.
Are these number bonds worksheets free and printable?
Yes. Every worksheet is a free, printable PDF with an answer key, and no sign-up is required.