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Missing Number Within 100 is a free printable Grade 2 maths worksheet on the unknown in a two-digit sentence, aligned to Common Core standard 2.NBT.B.5. It prints 12 questions with an answer key on its own sheet of paper, in 25 versions that each ask different questions, so no two pupils in the class work from the same page. Print it from the browser or download it as a PDF — no account, no email.

Set 1 of 25 · the same problems every time you open this link.

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All 25 sets ask different questions.

Missing Number Within 100

2.NBT.B.5

NameDate

Work out each answer.

1.20 + ___ = 45
2.44 + ___ = 87
3.12 + ___ = 52
4.43 + ___ = 55
5.29 + ___ = 49
6.16 + ___ = 39
7.11 + ___ = 36
8.44 + ___ = 69
9.11 + ___ = 25
10.19 + ___ = 63
11.43 + ___ = 71
12.24 + ___ = 54

LessonPrint · 2.NBT.B.5 · Set 1 · free to copy for classroom use

Answer key — Missing Number Within 100

Set 1. Prints on its own sheet.

  1. 1.25
  2. 2.43
  3. 3.40
  4. 4.12
  5. 5.20
  6. 6.23
  7. 7.25
  8. 8.25
  9. 9.14
  10. 10.44
  11. 11.28
  12. 12.30

Questions about Missing Number Within 100

What does the Missing Number Within 100 worksheet cover?

It practises the unknown in a two-digit sentence — 12 questions for Grade 2, all on Common Core 2.NBT.B.5: Add and subtract within 100 confidently. The instruction to pupils is “Work out each answer”, and the answer key follows on the next sheet.

Which Common Core standard does Missing Number Within 100 practise?

CCSS.MATH.CONTENT.2.NBT.B.5 — 2.NBT.B.5, in the Number & Operations in Base Ten domain for Grade 2. The published standard reads: “Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.” The worksheet assesses that standard rather than a paraphrase of it.

What age or grade is this worksheet for?

Missing Number Within 100 is written for Grade 2, typically ages 7-8. It is one of the sheets on 2.NBT.B.5, so it suits any pupil working at that standard — including older pupils revisiting it and younger ones working ahead.

Does Missing Number Within 100 come with an answer key?

Yes. All 12 answers are generated from the same problems as the questions, so the key cannot drift out of step with the sheet. It starts on a fresh sheet of paper, after the questions, so it is not handed out with the class by accident.

How many different versions of Missing Number Within 100 can I print?

25 — one per pupil, and all 25 ask different questions. Set 1 downloads the whole class as a single PDF. Every version is fixed to its own address, so a sheet printed today holds the same problems when you reopen it next week.

Is Missing Number Within 100 free to print and photocopy?

Yes. Missing Number Within 100, its answer key and its 25 versions are free to print and photocopy for your own class, with no account, no email capture and no subscription at the download step. Please do not resell them or republish them as your own.

More practice for 2.NBT.B.5

Add and subtract within 100 confidently.

All Grade 2 worksheets

Last reviewed 2026-09-05. Aligned to 2.NBT.B.5 of the Common Core State Standards for mathematics.