Add two two-digit numbers
23 + 14 can be shown by combining tens and ones.
2 tens and 1 more ten make 3 tens. 3 ones and 4 ones make 7 ones. So 23 + 14 = 37.
Year 2
Add and subtract numbers using concrete objects and pictorial representations, including two two-digit numbers
Use tens rods, ones cubes and clear picture models to show how addition and subtraction work, including with two two-digit numbers.
Lesson overview
Number - addition and subtraction
A picture model helps us see what is happening in a calculation. We can show each number with tens rods and ones cubes, then combine or remove the parts carefully. This helps us understand the method before moving on to more formal written work.
Subtract a two-digit number
46 - 12 means take away 1 ten and 2 ones.
4 tens become 3 tens and 6 ones become 4 ones, so 46 - 12 = 34.
A picture model shows what changed
34 + 20 changes the tens but keeps the ones the same.
3 tens plus 2 tens make 5 tens. The 4 ones stay the same, so the answer is 54.
Worked example
Work out 31 + 26 using the picture model.
- Show 31 as 3 tens and 1 one.
- Show 26 as 2 tens and 6 ones.
- Combine the tens first: 3 tens and 2 tens make 5 tens.
- Combine the ones next: 1 one and 6 ones make 7 ones.
- So 31 + 26 = 57.
Try it
Look at the picture or number sentence, then choose the answer that matches it.
Question 1
Question 2
Question 3
Question 4
Question 5
Common mistakes
Watch for these when you use picture models for addition and subtraction.
- Combining the digits without thinking about tens and ones.
- Taking away the wrong amount in a subtraction picture model.
- Trying to jump to the answer before reading what the visual is showing.
Related topics
These ideas support visual calculation methods in Year 2.
- Add and subtract numbers using concrete objects, pictorial representations, and mentally.
- Add tens and ones using unit cubes and tens rods.
- Use the column method for addition and subtraction without carrying or borrowing.