When you add 10, only the tens digit goes up by one. 10 more than 463 is 473. When you add 100, only the hundreds digit goes up by one: 100 more than 463 is 563.
Taking away works the same way in the other direction. 100 less than 463 is 363. Watch out when the digit is 9 or 0: 10 more than 395 is 405, because 9 tens and one more ten make a new hundred.
A place value chart helps: write the digits in hundreds, tens and ones columns and change just one column.
Worked example
What is 100 less than 708?
- Only the hundreds digit changes.
- 7 hundreds become 6 hundreds.
Answer:608
Key words
- hundreds digit
- the digit that shows hundreds
- more
- add
- less
- take away
Practise this
New questions every time.
Common Core-referenced: 2.NBT.B.8