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Missing First Number is a free printable Grade 1 maths worksheet on the unknown moved to the front of the sentence, aligned to Common Core standard 1.OA.B.4. It prints 16 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 5 of 25 · the same problems every time you open this link.

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Set 1 has all 25 in a single PDF. All 25 sets ask different questions.

Missing First Number

1.OA.B.4

NameDate

Work out each answer.

1.___ + 9 = 19
2.___ + 5 = 10
3.___ + 3 = 10
4.___ + 4 = 13
5.___ + 3 = 8
6.___ + 6 = 9
7.___ + 4 = 12
8.___ + 3 = 13
9.___ + 10 = 18
10.___ + 3 = 11
11.___ + 4 = 11
12.___ + 7 = 10
13.___ + 4 = 9
14.___ + 7 = 11
15.___ + 7 = 15
16.___ + 8 = 11

LessonPrint · 1.OA.B.4 · Set 5 · free to copy for classroom use

Answer key — Missing First Number

Set 5. Prints on its own sheet.

  1. 1.10
  2. 2.5
  3. 3.7
  4. 4.9
  5. 5.5
  6. 6.3
  7. 7.8
  8. 8.10
  9. 9.8
  10. 10.8
  11. 11.7
  12. 12.3
  13. 13.5
  14. 14.4
  15. 15.8
  16. 16.3

Last reviewed 2026-09-05. Aligned to 1.OA.B.4 of the Common Core State Standards for mathematics.