Addition and Subtraction Within 100: Mixed Practice
Forty problems of addition and subtraction within 100, written across in numbered rows rather than in columns, invite children aged 7-9 to use mental math instead of pencil routines.
2 A4 pages · for home and classroom use
Labugen
Addition and subtraction up to 100
set no. 204
- 1.96 + 1 =
- 2.91 - 10 =
- 3.60 + 16 =
- 4.29 + 34 =
- 5.94 - 90 =
- 6.14 - 6 =
- 7.44 + 17 =
- 8.45 + 42 =
- 9.84 - 61 =
- 10.17 + 32 =
- 11.59 - 56 =
- 12.11 - 3 =
- 13.15 + 23 =
- 14.25 - 10 =
- 15.6 - 5 =
- 16.91 - 84 =
- 17.37 + 12 =
- 18.73 - 15 =
- 19.37 - 18 =
- 20.76 + 23 =
- 21.14 - 13 =
- 22.68 + 28 =
- 23.24 + 5 =
- 24.67 + 16 =
- 25.5 + 75 =
- 26.68 - 29 =
- 27.45 + 23 =
- 28.48 + 29 =
- 29.2 + 25 =
- 30.39 - 28 =
- 31.15 + 39 =
- 32.8 - 5 =
- 33.73 + 15 =
- 34.34 - 12 =
- 35.88 - 36 =
- 36.94 + 4 =
- 37.35 - 28 =
- 38.19 + 73 =
- 39.25 - 4 =
- 40.34 + 7 =
How to use this worksheet
- Split the page into two sittings: problems 1-20 on one day and 21-40 on the next.
- Read the sign aloud first: plus and minus alternate unpredictably (21 additions, 19 subtractions).
- For each problem, ask your child to say the strategy in a few words, such as "tens then ones" or "count up".
- Check each half with the answer page and redo only the wrong ones.
What this worksheet teaches
Written horizontally, a problem like 29 + 34 cannot be solved by lining up digits, so children must think about tens and ones in their heads. Sixteen of the forty problems need regrouping (29 + 34, 68 + 28, 73 − 15), and the rest do not (45 + 42, 84 − 61). There are also quick ones, 6 − 5, 14 − 13 and 59 − 56, where spotting that the numbers are close saves time.
Mental math for horizontal problems
Split into tens and ones: 29 + 34 = 20 + 30 + 9 + 4 = 50 + 13 = 63. Round and adjust: 68 + 28 = 68 + 30 − 2 = 96, and 37 − 18 = 37 − 20 + 2 = 19. Count up when the numbers are close: from 84 to 91 is 7, from 90 to 94 is 4. Choosing the easiest route for each problem is itself the skill being practiced.