Step-by-step Maths Level 3: Counting in fifties and hundreds
Part of the Step-by-step Maths Level 3 counting to 1000 chapter. Chapter overview · whole chapter on one page
Counting in fifties and hundreds
A fifty is half of a hundred. When we count in fifties we say 50, 100, 150, 200 and so on.
Count in hundreds when you add 100 each time. Find the step first, then fill the gaps.
Key ideas
- Count in fifties: 50, 100, 150, 200.
- Count in hundreds: 100, 200, 300.
- Find the step before you fill a gap.
Method. Count on in fifties by adding or taking away 50 each time.
- Start at 450. We count from this number.450
- Add 50 each time. We count on in fifties.450 + 50 = 500; 500 + 50 = 550
- Write the numbers in order. These are the next numbers we said.500, 550, 600
Check. Count back in fifties from 600 to check. You reach 450.
Watch out. The step is 50. Each new number is 50 more than the last.
Method. Find the step, then count on in that step to fill each gap.
- Find the step. Each number is 10 more than the one before.490 - 480 = 10
- Fill the first gap. Add 10 to the number before the gap.490 + 10 = 500
- Fill the next gap. Add 10 again.510 + 10 = 520
- Write the missing numbers. Read them in order.500, 520
Check. Count on in 10s from 480: 480, 490, 500, 510, 520. It fits.
Watch out. Check the step with the numbers either side of a gap.
Method. Count back in hundreds by adding or taking away 100 each time.
- Start at 700. We count from this number.700
- Take 100 each time. We count back in hundreds.700 - 100 = 600; 600 - 100 = 500
- Write the numbers in order. These are the next numbers we said.600, 500, 400
Check. Count on in hundreds from 400 to check. You reach 700.
Watch out. The step is 100. Each new number is 100 less than the last.
Watch out
Watch out. In a count of fifties, the step is 50, not 5. After 450 comes 500, not 455.
Exam tip
Grown-up tip. Ask the child to say the step out loud before counting. Clapping on each number helps.
Exercise 1C Practice: counting in fifties, hundreds and gaps
Non-calculatorMethod. Count on in hundreds by adding or taking away 100 each time.
- Start at 600. We count from this number.600
- Add 100 each time. We count on in hundreds.600 + 100 = 700; 700 + 100 = 800
- Write the numbers in order. These are the next numbers we said.700, 800, 900
Check. Count back in hundreds from 900 to check. You reach 600.
Watch out. The step is 100. Each new number is 100 more than the last.
Method. Count on in fifties by adding or taking away 50 each time.
- Start at 100. We count from this number.100
- Add 50 each time. We count on in fifties.100 + 50 = 150; 150 + 50 = 200
- Write the numbers in order. These are the next numbers we said.150, 200, 250
Check. Count back in fifties from 250 to check. You reach 100.
Watch out. The step is 50. Each new number is 50 more than the last.
Method. Count on in fifties by adding or taking away 50 each time.
- Start at 0. We count from this number.0
- Add 50 each time. We count on in fifties.0 + 50 = 50; 50 + 50 = 100
- Write the numbers in order. These are the next numbers we said.50, 100, 150
Check. Count back in fifties from 150 to check. You reach 0.
Watch out. The step is 50. Each new number is 50 more than the last.
Method. Count back in fifties by adding or taking away 50 each time.
- Start at 600. We count from this number.600
- Take 50 each time. We count back in fifties.600 - 50 = 550; 550 - 50 = 500
- Write the numbers in order. These are the next numbers we said.550, 500, 450
Check. Count on in fifties from 450 to check. You reach 600.
Watch out. The step is 50. Each new number is 50 less than the last.
Method. Count on in hundreds by adding or taking away 100 each time.
- Start at 0. We count from this number.0
- Add 100 each time. We count on in hundreds.0 + 100 = 100; 100 + 100 = 200
- Write the numbers in order. These are the next numbers we said.100, 200, 300
Check. Count back in hundreds from 300 to check. You reach 0.
Watch out. The step is 100. Each new number is 100 more than the last.
Method. Count on in hundreds by adding or taking away 100 each time.
- Start at 700. We count from this number.700
- Add 100 each time. We count on in hundreds.700 + 100 = 800; 800 + 100 = 900
- Write the numbers in order. These are the next numbers we said.800, 900, 1000
Check. Count back in hundreds from 1000 to check. You reach 700.
Watch out. The step is 100. Each new number is 100 more than the last.
Method. Count on in hundreds by adding or taking away 100 each time.
- Start at 200. We count from this number.200
- Add 100 each time. We count on in hundreds.200 + 100 = 300; 300 + 100 = 400
- Write the numbers in order. These are the next numbers we said.300, 400, 500
Check. Count back in hundreds from 500 to check. You reach 200.
Watch out. The step is 100. Each new number is 100 more than the last.
Method. Count back in hundreds by adding or taking away 100 each time.
- Start at 800. We count from this number.800
- Take 100 each time. We count back in hundreds.800 - 100 = 700; 700 - 100 = 600
- Write the numbers in order. These are the next numbers we said.700, 600, 500
Check. Count on in hundreds from 500 to check. You reach 800.
Watch out. The step is 100. Each new number is 100 less than the last.
Method. Find the step, then count on in that step to fill each gap.
- Find the step. Each number is 1 more than the one before.419 - 418 = 1
- Fill the first gap. Add 1 to the number before the gap.419 + 1 = 420
- Fill the next gap. Add 1 again.421 + 1 = 422
- Write the missing numbers. Read them in order.420, 422
Check. Count on in 1s from 418: 418, 419, 420, 421, 422. It fits.
Watch out. Check the step with the numbers either side of a gap.
Method. Find the step, then count on in that step to fill each gap.
- Find the step. Each number is 10 more than the one before.20 - 10 = 10
- Fill the first gap. Add 10 to the number before the gap.20 + 10 = 30
- Fill the next gap. Add 10 again.40 + 10 = 50
- Write the missing numbers. Read them in order.30, 50
Check. Count on in 10s from 10: 10, 20, 30, 40, 50. It fits.
Watch out. Check the step with the numbers either side of a gap.
Method. Find the step, then count on in that step to fill each gap.
- Find the step. Each number is 100 more than the one before.600 - 500 = 100
- Fill the first gap. Add 100 to the number before the gap.600 + 100 = 700
- Fill the next gap. Add 100 again.800 + 100 = 900
- Write the missing numbers. Read them in order.700, 900
Check. Count on in 100s from 500: 500, 600, 700, 800, 900. It fits.
Watch out. Check the step with the numbers either side of a gap.
Method. Find the step, then count on in that step to fill each gap.
- Find the step. Each number is 5 more than the one before.13 - 8 = 5
- Fill the first gap. Add 5 to the number before the gap.13 + 5 = 18
- Fill the next gap. Add 5 again.23 + 5 = 28
- Write the missing numbers. Read them in order.18, 28
Check. Count on in 5s from 8: 8, 13, 18, 23, 28. It fits.
Watch out. Check the step with the numbers either side of a gap.
Method. Find the step, then count on in that step to fill each gap.
- Find the step. Each number is 5 more than the one before.551 - 546 = 5
- Fill the first gap. Add 5 to the number before the gap.551 + 5 = 556
- Fill the next gap. Add 5 again.561 + 5 = 566
- Write the missing numbers. Read them in order.556, 566
Check. Count on in 5s from 546: 546, 551, 556, 561, 566. It fits.
Watch out. Check the step with the numbers either side of a gap.
Method. Find the step, then count on in that step to fill each gap.
- Find the step. Each number is 1 more than the one before.852 - 851 = 1
- Fill the first gap. Add 1 to the number before the gap.852 + 1 = 853
- Fill the next gap. Add 1 again.854 + 1 = 855
- Write the missing numbers. Read them in order.853, 855
Check. Count on in 1s from 851: 851, 852, 853, 854, 855. It fits.
Watch out. Check the step with the numbers either side of a gap.
Method. Find the step, then count on in that step to fill each gap.
- Find the step. Each number is 5 more than the one before.905 - 900 = 5
- Fill the first gap. Add 5 to the number before the gap.905 + 5 = 910
- Fill the next gap. Add 5 again.915 + 5 = 920
- Write the missing numbers. Read them in order.910, 920
Check. Count on in 5s from 900: 900, 905, 910, 915, 920. It fits.
Watch out. Check the step with the numbers either side of a gap.
Method. Find the step, then count on in that step to fill each gap.
- Find the step. Each number is 2 more than the one before.596 - 594 = 2
- Fill the first gap. Add 2 to the number before the gap.596 + 2 = 598
- Fill the next gap. Add 2 again.600 + 2 = 602
- Write the missing numbers. Read them in order.598, 602
Check. Count on in 2s from 594: 594, 596, 598, 600, 602. It fits.
Watch out. Check the step with the numbers either side of a gap.