Step-by-step Maths Level 1: Adding three numbers
Part of the Step-by-step Maths Level 1 adding within 10 chapter. Chapter overview · whole chapter on one page
Adding three numbers
To add three numbers, add two of them first. Then add the third number to the total.
Key ideas
- Add two numbers first.
- Then add the third number.
- Keep the total from the first step.
Method. Add the first two numbers. Then add the third.
- Add the first two. 2 + 3 = 5.2 + 3 = 5
- Add the third number. 5 + 1 = 6.5 + 1 = 6
- Write the answer. 6
Check. Add in another order: 3 + 1 = 4, then 4 + 2 = 6. It matches.
Watch out. Keep the first total in your head, then add the next number.
Method. Add the first two numbers. Then add the third.
- Add the first two. 4 + 1 = 5.4 + 1 = 5
- Add the third number. 5 + 2 = 7.5 + 2 = 7
- Write the answer. 7
Check. Add the last two first: 1 + 2 = 3, then 4 + 3 = 7. It matches.
Watch out. Do not add all three in your head at once. Do one step at a time.
Method. Add the first two numbers. Then add the third.
- Add the first two. 3 + 3 = 6.3 + 3 = 6
- Add the third number. 6 + 3 = 9.6 + 3 = 9
- Write the answer. 9
Check. Three threes make nine. It matches.
Watch out. Check that the total is not more than 10.
Watch out
Watch out. Work out two numbers at a time. Do not skip the middle total.
Exam tip
Grown-up tip. Use three piles of counters. Add two piles, write the total, then add the third pile.
Exercise 6D Adding three numbers
Non-calculatorMethod. Add two numbers first, then add the third.
- Add the first two numbers. Put 2 and 6 together.2 + 6 = 8
- Add the third number. Put 8 and 2 together.8 + 2 = 10
- Write the answer. 10
Check. Add in a different order: 2 + 2 = 4, then add 6: 10. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 1 and 3 together.1 + 3 = 4
- Add the third number. Put 4 and 6 together.4 + 6 = 10
- Write the answer. 10
Check. Add in a different order: 1 + 6 = 7, then add 3: 10. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 3 and 3 together.3 + 3 = 6
- Add the third number. Put 6 and 4 together.6 + 4 = 10
- Write the answer. 10
Check. Add in a different order: 3 + 4 = 7, then add 3: 10. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 4 and 1 together.4 + 1 = 5
- Add the third number. Put 5 and 5 together.5 + 5 = 10
- Write the answer. 10
Check. Add in a different order: 4 + 5 = 9, then add 1: 10. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 1 and 1 together.1 + 1 = 2
- Add the third number. Put 2 and 5 together.2 + 5 = 7
- Write the answer. 7
Check. Add in a different order: 1 + 5 = 6, then add 1: 7. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 6 and 1 together.6 + 1 = 7
- Add the third number. Put 7 and 1 together.7 + 1 = 8
- Write the answer. 8
Check. Add in a different order: 6 + 1 = 7, then add 1: 8. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 3 and 4 together.3 + 4 = 7
- Add the third number. Put 7 and 3 together.7 + 3 = 10
- Write the answer. 10
Check. Add in a different order: 3 + 3 = 6, then add 4: 10. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 4 and 1 together.4 + 1 = 5
- Add the third number. Put 5 and 2 together.5 + 2 = 7
- Write the answer. 7
Check. Add in a different order: 4 + 2 = 6, then add 1: 7. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 6 and 2 together.6 + 2 = 8
- Add the third number. Put 8 and 1 together.8 + 1 = 9
- Write the answer. 9
Check. Add in a different order: 6 + 1 = 7, then add 2: 9. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 4 and 1 together.4 + 1 = 5
- Add the third number. Put 5 and 3 together.5 + 3 = 8
- Write the answer. 8
Check. Add in a different order: 4 + 3 = 7, then add 1: 8. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 6 and 2 together.6 + 2 = 8
- Add the third number. Put 8 and 1 together.8 + 1 = 9
- Write the answer. 9
Check. Add in a different order: 6 + 1 = 7, then add 2: 9. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 5 and 1 together.5 + 1 = 6
- Add the third number. Put 6 and 1 together.6 + 1 = 7
- Write the answer. 7
Check. Add in a different order: 5 + 1 = 6, then add 1: 7. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 2 and 3 together.2 + 3 = 5
- Add the third number. Put 5 and 1 together.5 + 1 = 6
- Write the answer. 6
Check. Add in a different order: 2 + 1 = 3, then add 3: 6. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 2 and 4 together.2 + 4 = 6
- Add the third number. Put 6 and 1 together.6 + 1 = 7
- Write the answer. 7
Check. Add in a different order: 2 + 1 = 3, then add 4: 7. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 5 and 1 together.5 + 1 = 6
- Add the third number. Put 6 and 4 together.6 + 4 = 10
- Write the answer. 10
Check. Add in a different order: 5 + 4 = 9, then add 1: 10. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.
Method. Add two numbers first, then add the third.
- Add the first two numbers. Put 3 and 2 together.3 + 2 = 5
- Add the third number. Put 5 and 3 together.5 + 3 = 8
- Write the answer. 8
Check. Add in a different order: 3 + 3 = 6, then add 2: 8. ✓
Watch out. Work in pairs, one step at a time. Keep the total in your head.