Step-by-step Maths Level 3: Ten more, ten less, 100 more, 100 less
Part of the Step-by-step Maths Level 3 counting to 1000 chapter. Chapter overview · whole chapter on one page
Ten more, ten less, 100 more, 100 less
When we add 10, only the tens digit changes. When we add 100, only the hundreds digit changes.
The other digits stay the same. This is quick to see if you look at the digits.
Key ideas
- 10 more changes the tens digit.
- 10 less changes the tens digit.
- 100 more changes the hundreds digit.
- The other digits stay the same.
Method. Change only the tens digit when we go more than the number.
- Start at 374. We begin with this number.374
- Change the tens digit. Only the tens digit changes. The others stay the same.374 + 10 = 384
- Write the answer. This is the new number.384
Check. 10 less than 384 is 374. It works.
Watch out. Only the tens digit changes. Keep the other digits the same.
Method. Change only the hundreds digit when we go less than the number.
- Start at 805. We begin with this number.805
- Change the hundreds digit. Only the hundreds digit changes. The others stay the same.805 - 100 = 705
- Write the answer. This is the new number.705
Check. 100 more than 705 is 805. It works.
Watch out. Only the hundreds digit changes. Keep the other digits the same.
Method. Count on in tens by adding or taking away 10 each time.
- Start at 340. We count from this number.340
- Add 10 each time. We count on in tens.340 + 10 = 350; 350 + 10 = 360
- Write the numbers in order. These are the next numbers we said.350, 360, 370
Check. Count back in tens from 370 to check. You reach 340.
Watch out. The step is 10. Each new number is 10 more than the last.
Watch out
Watch out. 10 more than 396 is 406, not 496. The 9 tens and 1 ten make 10 tens, which is 1 hundred, so the 3 hundreds becomes 4 hundreds.
Exam tip
Grown-up tip. Use base-ten blocks. Ask the child to add one ten stick, then say which digit changed.
Exercise 1B Practice: 10 and 100 more or less
Non-calculatorMethod. Change only the tens digit when we go more than the number.
- Start at 295. We begin with this number.295
- Change the tens digit. Only the tens digit changes. The others stay the same.295 + 10 = 305
- Write the answer. This is the new number.305
Check. 10 less than 305 is 295. It works.
Watch out. Only the tens digit changes. Keep the other digits the same.
Method. Change only the tens digit when we go more than the number.
- Start at 113. We begin with this number.113
- Change the tens digit. Only the tens digit changes. The others stay the same.113 + 10 = 123
- Write the answer. This is the new number.123
Check. 10 less than 123 is 113. It works.
Watch out. Only the tens digit changes. Keep the other digits the same.
Method. Change only the hundreds digit when we go more than the number.
- Start at 217. We begin with this number.217
- Change the hundreds digit. Only the hundreds digit changes. The others stay the same.217 + 100 = 317
- Write the answer. This is the new number.317
Check. 100 less than 317 is 217. It works.
Watch out. Only the hundreds digit changes. Keep the other digits the same.
Method. Change only the ones digit when we go less than the number.
- Start at 256. We begin with this number.256
- Change the ones digit. Only the ones digit changes. The others stay the same.256 - 1 = 255
- Write the answer. This is the new number.255
Check. 1 more than 255 is 256. It works.
Watch out. Only the ones digit changes. Keep the other digits the same.
Method. Change only the ones digit when we go less than the number.
- Start at 956. We begin with this number.956
- Change the ones digit. Only the ones digit changes. The others stay the same.956 - 1 = 955
- Write the answer. This is the new number.955
Check. 1 more than 955 is 956. It works.
Watch out. Only the ones digit changes. Keep the other digits the same.
Method. Change only the hundreds digit when we go less than the number.
- Start at 372. We begin with this number.372
- Change the hundreds digit. Only the hundreds digit changes. The others stay the same.372 - 100 = 272
- Write the answer. This is the new number.272
Check. 100 more than 272 is 372. It works.
Watch out. Only the hundreds digit changes. Keep the other digits the same.
Method. Change only the tens digit when we go less than the number.
- Start at 792. We begin with this number.792
- Change the tens digit. Only the tens digit changes. The others stay the same.792 - 10 = 782
- Write the answer. This is the new number.782
Check. 10 more than 782 is 792. It works.
Watch out. Only the tens digit changes. Keep the other digits the same.
Method. Change only the hundreds digit when we go less than the number.
- Start at 146. We begin with this number.146
- Change the hundreds digit. Only the hundreds digit changes. The others stay the same.146 - 100 = 46
- Write the answer. This is the new number.46
Check. 100 more than 46 is 146. It works.
Watch out. Only the hundreds digit changes. Keep the other digits the same.
Method. Change only the tens digit when we go more than the number.
- Start at 795. We begin with this number.795
- Change the tens digit. Only the tens digit changes. The others stay the same.795 + 10 = 805
- Write the answer. This is the new number.805
Check. 10 less than 805 is 795. It works.
Watch out. Only the tens digit changes. Keep the other digits the same.
Method. Change only the hundreds digit when we go more than the number.
- Start at 812. We begin with this number.812
- Change the hundreds digit. Only the hundreds digit changes. The others stay the same.812 + 100 = 912
- Write the answer. This is the new number.912
Check. 100 less than 912 is 812. It works.
Watch out. Only the hundreds digit changes. Keep the other digits the same.
Method. Change only the tens digit when we go less than the number.
- Start at 591. We begin with this number.591
- Change the tens digit. Only the tens digit changes. The others stay the same.591 - 10 = 581
- Write the answer. This is the new number.581
Check. 10 more than 581 is 591. It works.
Watch out. Only the tens digit changes. Keep the other digits the same.
Method. Change only the tens digit when we go less than the number.
- Start at 623. We begin with this number.623
- Change the tens digit. Only the tens digit changes. The others stay the same.623 - 10 = 613
- Write the answer. This is the new number.613
Check. 10 more than 613 is 623. It works.
Watch out. Only the tens digit changes. Keep the other digits the same.
Method. Change only the ones digit when we go less than the number.
- Start at 279. We begin with this number.279
- Change the ones digit. Only the ones digit changes. The others stay the same.279 - 1 = 278
- Write the answer. This is the new number.278
Check. 1 more than 278 is 279. It works.
Watch out. Only the ones digit changes. Keep the other digits the same.
Method. Change only the hundreds digit when we go more than the number.
- Start at 781. We begin with this number.781
- Change the hundreds digit. Only the hundreds digit changes. The others stay the same.781 + 100 = 881
- Write the answer. This is the new number.881
Check. 100 less than 881 is 781. It works.
Watch out. Only the hundreds digit changes. Keep the other digits the same.
Method. Change only the tens digit when we go less than the number.
- Start at 896. We begin with this number.896
- Change the tens digit. Only the tens digit changes. The others stay the same.896 - 10 = 886
- Write the answer. This is the new number.886
Check. 10 more than 886 is 896. It works.
Watch out. Only the tens digit changes. Keep the other digits the same.
Method. Change only the hundreds digit when we go more than the number.
- Start at 710. We begin with this number.710
- Change the hundreds digit. Only the hundreds digit changes. The others stay the same.710 + 100 = 810
- Write the answer. This is the new number.810
Check. 100 less than 810 is 710. It works.
Watch out. Only the hundreds digit changes. Keep the other digits the same.