Lesson 4.1 · Adding and Subtracting Within 1,000
10 or 100 more and less
What is 100 more than 245? You don't need to count all the way up. Only one digit changes. Let's see which one.
100 more and 100 less
245 has 2 hundreds, 4 tens and 5 ones.
100 more means 1 more hundred. 2 hundreds become 3 hundreds.
The tens and ones stay the same. So 100 more than 245 is 345.
100 less works the same way. 2 hundreds become 1 hundred. So 100 less than 245 is 145.
Here are hops of 100 on a number line. Look at the hundreds digit: 1, 2, 3, 4.
10 more and 10 less
10 more means 1 more ten. Only the tens digit changes.
10 more than 245 is 255. 10 less than 245 is 235.
Count back by tens from 560: 550, 540. The hundreds and ones stay put.
Which digit changes?
- 100 more or 100 less: change the hundreds digit by 1.
- 10 more or 10 less: change the tens digit by 1.
The other digits stay the same.
Worked example: 10 more than 356
356 has 5 tens. 5 tens become 6 tens.
The 3 hundreds and 6 ones stay. The answer is 366.
Worked example: 100 less than 482
482 has 4 hundreds. 4 hundreds become 3 hundreds.
The 8 tens and 2 ones stay. The answer is 382.
Worked example: 10 more than 492
492 has 9 tens. 9 tens + 1 ten = 10 tens.
10 tens make 1 hundred! So 4 hundreds become 5 hundreds, and there are 0 tens.
The answer is 502.
Common mistake
Watch out when the tens digit is 9 (going up) or 0 (going down). 10 more than 492 is 502, not 4,102. 10 less than 604 is 594, not 6,094.
Practice
What is 10 more than 243?
Type a number.
What is 100 more than 516?
Type a number.
What is 10 less than 875?
Type a number.
What is 100 less than 309?
Type a number.
What is 10 more than 697?
Fill in the blank: 100 less than ___ is 462.
Type a number.
Mia has 328 stickers. She gets 100 more. Then she gives 10 to a friend. How many stickers does she have now?
Type a number.
What is 10 less than 604?
Type a number.