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Adding to 100 — Mixed is a free printable Grade 1 math worksheet on judging two-digit sums, with the unmade ten as the trap, aligned to Common Core standard 1.NBT.C.4. 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 students in the class work from the same page. Print it from the browser or download it as a PDF — no account, no email.

Set 24 of 25 · the same problems every time you open this link.

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One paper per student

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

Adding to 100 — Mixed

1.NBT.C.4

NameDate

Write true or false. If false, write the right answer.

1.True or false? 18 + 5 = 23
2.True or false? 29 + 2 = 21
3.True or false? 35 + 9 = 34
4.True or false? 57 + 6 = 53
5.True or false? 87 + 9 = 96
6.True or false? 15 + 8 = 23
7.True or false? 28 + 5 = 23
8.True or false? 47 + 4 = 41
9.True or false? 27 + 7 = 34
10.True or false? 16 + 4 = 20
11.True or false? 15 + 9 = 14
12.True or false? 44 + 9 = 53

LessonPrint · 1.NBT.C.4 · Set 24 · free to copy for classroom use

Answer key — Adding to 100 — Mixed

Set 24. Prints on its own sheet.

  1. 1.true
  2. 2.false — 31
  3. 3.false — 44
  4. 4.false — 63
  5. 5.true
  6. 6.true
  7. 7.false — 33
  8. 8.false — 51
  9. 9.true
  10. 10.true
  11. 11.false — 24
  12. 12.true

Last reviewed 2026-09-05. Aligned to 1.NBT.C.4 of the Common Core State Standards for Mathematics.