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➕ 1st grade math · Add & Subtract

Add with tens and ones

Add tens to tens. 3 tens + 4 tens = 7 tens = 70.

Worked example

70 + 20 = ?
Answer: 90
7 tens + 2 tens = 9 tens, which is 90. Answer: 90.

For grown-ups: Add within 100 with models (2-digit + 1-digit, + multiples of 10). Below: three problems to try with the worked answers, and a free printable sheet. Children can practise the same skill as a game, with no sign-up and no ads.

  • CCSS 1.NBT.C.4
What this practises, for teachers

Practices add within 100 with models (2-digit + 1-digit, + multiples of 10) (1.NBT.C.4). A printable sheet with its answer key, worked answers on the page, no accounts.

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For your class

🖨️ Printable sheet and key

On the board with this skill:

More printables, with answer keys, for this grade:

Try three

  1. 20 + 80 = ?
    Show the answer and how
    Answer: 100
    2 tens + 8 tens = 10 tens, which is 100. Answer: 100.
  2. 40 + 20 = ?
    Show the answer and how
    Answer: 60
    4 tens + 2 tens = 6 tens, which is 60. Answer: 60.
  3. 73 + 5 = ?
    Show the answer and how
    Answer: 78
    Add the ones: 3 + 5 = 8. The tens stay the same: 78. Answer: 78.

Before and after

Learn first: Doubles and make-a-ten tricks (1st)

Comes next: Story problems to 100 (2nd), Add and subtract to 100 (2nd)

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Add with tens and ones (1st grade)

  1. 60 + 30 = ?
  2. 70 + 30 = ?
  3. 70 + 10 = ?
  4. 50 + 40 = ?
  5. 60 + 30 = ?
  6. 20 + 40 = ?
  7. 30 + 50 = ?
  8. 10 + 90 = ?
  9. 60 + 20 = ?
  10. 30 + 60 = ?
  11. 76 + 20 = ?
  12. 50 + 20 = ?

Answer key

  1. 90
  2. 100
  3. 80
  4. 90
  5. 90
  6. 60
  7. 80
  8. 100
  9. 80
  10. 90
  11. 96
  12. 70

More 1st grade skills: all 1st grade math skills, or every grade at math skills.