Addition to a thousand
You learn to add and subtract to 1000 in round steps, so you never work with awkward numbers all at once.
How to work it out
- If numbers are round, drop the zero: 460 + 80 becomes 46 + 8, then put the zero back.
- If calculating with a whole hundred, only the hundreds digit changes.
- Otherwise: do tens first, then ones.
460 + 80
- Both numbers are round, so leave off the 0: 46 + 8 = 54.
- Put the 0 back.
- So 460 + 80 = 540.
More examples
563 − 200
- Only the hundreds change: 500 − 200 = 300.
- The 63 stays the same: 300 + 63 = 363.
875 + 25
- First add the tens: 875 + 20 = 895.
- Then add the ones: 895 + 5 = 900.