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2nd grade · Math · Unit 15 of 16

Add & Subtract to 1000

Hundreds, tens and ones

What your child practices

Adding and subtracting three-digit numbers using place value, and adding or taking away 10 or 100 in their head.

Arizona Academic Standards learning standard: 2.NBT.B.7; 2.NBT.B.8 · adding and subtracting within 1000 using place value, and mentally adding or subtracting 10 or 100

How we explain it

Children can open this short lesson before they practice.

  1. Add the hundreds, then the tens, then the ones.
  2. Regroup 10 ones as a ten, or 10 tens as a hundred.
  3. 10 more or 100 more changes just one digit.

Example: What is 345 + 132? 300 + 100 = 400. 40 + 30 = 70. 5 + 2 = 7. 400 + 70 + 7 = 477. Answer: 477

Add & Subtract to 1000 in Arizona

In the Arizona Academic Standards, this is unit 15 of 16 in 2nd grade Math, after Arrays and before Bar Graphs.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Arizona Department of Education

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    What is 100 less than 123?

    • 113
    • 122
    • 24
    • 20
    • 23

  2. Question 2

    What is 823 + 108?

    823 + 108 = ?

    • 931
    • 1031
    • 941
    • 831
    • 921

  3. Question 3

    210 + ? = 310. What number is missing?

    • 110
    • 10
    • 100
    • 200

  4. Question 4

    What is 845 − 551?

    845 − 551 = ?

    • 297
    • 304
    • 294
    • 394
    • 284

  5. Question 5

    What is 200 + 60 + 7?

    200 + 60 + 7 = ?

    • 276
    • 15
    • 267
    • 367

  6. Question 6

    680 + ? = 980. What number is missing?

    • 310
    • 300
    • 200
    • 30

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