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Missing Addends (Sum to 20) Worksheets for 1st Grade

Solve for the missing number in an addition sentence with sums up to 20. 15 free printable worksheets, each with an answer key.

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Free Missing Addends (Sum to 20) Worksheets

Click a worksheet to open the PDF, or grab the matching answer key. Every sheet prints on one page.

Missing Addends (Sum to 20): what children learn

This extends missing-addend practice past single digits — the same "work backward" thinking now applies to sums up to 20, matching where 1st grade addition fluency is headed.

Missing Addends (Sum to 20): worked example

8 + __ = 15 7

Think "8 plus what equals 15?" Counting on from 8 to 15 takes 7 steps, so the missing number is 7.

Missing Addends (Sum to 20): a common mistake to watch for

Kids sometimes just add the two visible numbers (8 + 15 = 23) instead of recognizing one of them is the answer, not an addend — reading the equation aloud as a question helps.

Missing Addends (Sum to 20): how to help at home or in class

Cover one number in a short addition sentence with a sticky note. Have your child say the sentence as a question, such as eight plus what makes fifteen, and then count up from the small number to reach the total, tracking the jumps on fingers. You can also use a number line in chalk outdoors. Make your own puzzles from the numbers on license plates or books. When your child reaches the total reliably, link it to subtraction.

What is on these Missing Addends (Sum to 20) worksheets

This set has 15 different worksheets for 1st grade, with 23 questions on each and a matching answer key for every sheet. The instruction printed on each worksheet is: “Find the missing number.”

Example questions like the ones on these worksheets, with their answers:

  • 3 + __ = 63
  • __ + 4 = 1612
  • __ + 14 = 206
  • __ + 1 = 1110
  • 2 + __ = 31
  • __ + 5 = 1510
  • 15 + __ = 183
  • __ + 2 = 2018

Every answer on every sheet is checked by a separate program before the worksheet is published. How we check answers

Related Addition worksheets for 1st grade

Number Bonds — Sums with 10
Find the missing part of pairs that add up to 10 ("friends of 10").
Near Doubles
Add two numbers that are close together using a doubles fact as a shortcut.
Complete the Next Ten
Find how much to add to reach the next multiple of ten.
Whole Tens — Missing Addend
Solve for the missing number when every value is a whole ten.
Add Whole Tens
Add two multiples of ten together (e.g. 30 + 40).
Adding Doubles Plus 1
Add two numbers that are exactly 1 apart, using a doubles fact as a shortcut.
All Addition worksheets
See every addition topic for 1st grade