Taking away to 100
We can take away small numbers and tens from numbers up to 100. Just like adding, we keep the tens and the ones apart. Take away the ones from the ones, and the tens from the tens, then put them back together. Taking away whole tens is easy, like 50 − 20 = 30.
Key idea
Subtract tens from tens, ones from ones. 28 − 4: keep 20, then 8 − 4 = 4, so the answer is 24.
Take away step by step
Worked example
Take away 15 − 3. Keep the ten (10). Now the ones: 5 − 3 = 2. Put them back: 10 and 2 make 12. So 15 − 3 = 12.
Remember
- Keep tens and ones apart.
- Take away ones first.
- Whole tens are quick.
- Check by adding back.