Grade 1 Addition Missing Number
Grade 1 addition missing number sheet: 24 problems on sums within 20, two-digit plus one-digit within 100.
Download
Three different problem sets — same skill, same layout, fresh numbers.
Preview — Set A
Find the number that belongs in each blank.
- 1.4 + 13 = ___
- 2.43 + 5 = ___
- 3.1 + 9 = ___
- 4.80 + ___ = 89
- 5.11 + 9 = ___
- 6.66 + 7 = ___
- 7.13 + ___ = 18
- 8.44 + ___ = 50
- 9.___ + 17 = 20
- 10.46 + ___ = 51
- 11.12 + ___ = 15
- 12.34 + 8 = ___
- 13.14 + ___ = 16
- 14.39 + 6 = ___
- 15.___ + 4 = 17
- 16.___ + 7 = 70
- 17.5 + 4 = ___
- 18.47 + ___ = 48
- 19.15 + 3 = ___
- 20.28 + 4 = ___
- 21.13 + ___ = 20
- 22.45 + ___ = 51
- 23.1 + 6 = ___
- 24.73 + ___ = 81
What this worksheet covers
24 addition problems fill this missing number page; problem 9 asks "___ + 17 = 20", and the sheet stays at that level throughout. The blank moves between positions from problem to problem, so no single procedure clears the page and the numbers run as high as 89. Further down, problem 17 asks "5 + 4 = ___". Common Core 1.OA.6 is the slot this page fills.
Skills practised
At grade 1, addition is about fact fluency within 20, three addends, and two-digit plus one-digit numbers, and this sheet takes one slice of that. What a student is asked to do here is sums within 20 and two-digit plus one-digit within 100. Concretely, the sheet tests whether a student can reason backwards from a result to a missing part. Nineteen different answers appear across the 24 problems, so a student cannot copy one result down the page.
About the missing number format
The 24 problems here move the unknown around, so a student solves for a missing part as often as for a result; problem 9, "___ + 17 = 20" is one of them. A blank on the left or in the middle turns addition into its own inverse and builds the fact-family idea that subtraction rests on.
Set A, Set B and Set C
The three sets come from the same generator with three different seeds: same skill, same layout, fresh numbers, and an answer key computed with the problems. Where Set A's problem 13 is "14 + ___ = 16", Set B's is "___ + 2 = 19".
How to use this worksheet
Grade 1 attention runs short, so split these 24 addition problems over two or three sittings rather than pushing through in one; a number line or counters within reach is a strategy, not a failure. Keep the key face down until all 24 problems are finished, then go through the misses together rather than only totalling the score.
One mistake to watch for
Answers to the missing-number problems are the sum of the two visible numbers. Watch problem 17 of this missing number — "5 + 4 = ___" — for this one.
The equals sign is being read as "write the answer here", not as a statement of balance.
Read the equation aloud as a sentence — "something plus five is twelve" — before touching the pencil.
Other grade 1 addition formats
The same skill in the other formats available at this grade.
- Drill — Grade 1 Addition Practice, 18 problems
- Timed Drill — Grade 1 Addition Timed Drill, 60 problems
- Mixed Review — Adding Three Numbers — Grade 1 Word Problems, 22 problems
- Word Problems — Adding Up: Grade 1 Word Problems Within 20, 22 problems
- Vertical Format — 1.NBT.4 — Adding Within 100: Two-Digit & One-Digit Numbers, 22 problems
A step either side
The same format one grade down and one grade up — the easier sheet is often the faster fix when this one is not landing.
- Kindergarten Addition Missing Number — kindergarten, 20 problems
- Grade 2 Addition Missing Number — grade 2, 24 problems
Missing Number sheets in other grade 1 topics
Six PDFs, no sign-up: three versions of this grade 1 addition missing number and three answer keys, each 24 problems long.