Maths Library

Addition Within 100: Year 3 maths

This topic builds mental and informal written addition strategies for two-digit numbers with and without bridging ten. Pupils practise number line jumps, partitioning tens and ones, and consolidating basic two-digit sum fluency.

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What this covers

Addition Within 100 is taught in Year 3 (age 8 to 9) as a main teaching focus. It sits in the Number strand.

Worked example

Calculate: 38 + 25

  1. Partition 25 into 20 and 5.
  2. Add the tens: 38 + 20 = 58.
  3. Add the ones: 58 + 5 = 63.

Answer: 63

Difficulty scale

The sheet generator offers five difficulty settings for this topic.

  1. Adding a 1-digit number to a 2-digit number without bridging ten (e.g., 23 + 4)
  2. Adding a 1-digit number to a 2-digit number with bridging ten (e.g., 28 + 6)
  3. Adding a multiple of 10 to a 2-digit number (e.g., 45 + 30)
  4. Adding two 2-digit numbers without regrouping (e.g., 42 + 35)
  5. Adding two 2-digit numbers with regrouping across ten (e.g., 47 + 38)

Common mistakes

  • Adding tens to ones by concatenating digits without place value alignment
  • Forgetting to add the bridged ten when sum of ones exceeds 9

Curriculum links

Indicative matches to Australian Curriculum v9. Check wording and codes against the official document.

  • AC9M3N02 Add and subtract two- and three-digit numbers using mental and written strategies.

Sample sheet and answers

Six questions at the level's usual difficulty. Open the editor to change, add or regenerate any of them.

Addition Within 100

Year 3 maths

Qs
6
Marks
12
NameDateScore / 12
1.
59 + 24 =
[2]
2.
17 + 65 =
[2]
3.
32 + 12 =
[2]
4.
55 + 45 =
[2]
5.
46 + 37 =
[2]
6.
48 + 40 =
[2]

Answer key

  1. 8359 + 24 = 83
  2. 8217 + 65 = 82
  3. 4432 + 12 = 44
  4. 10055 + 45 = 100
  5. 8346 + 37 = 83
  6. 8848 + 40 = 88