Rounding
Round whole numbers to a given place value.
Objective
Round whole numbers to a given place value.
What it means
Rounding replaces a number with a nearby number that is easier to work with, based on a chosen place value.
See it
Use this model while you read. Move it around to see what the math is doing.
The point is on 6. Jumps of 2.
Key terms
- Rounding digit
- The digit in the place you are rounding to.
- Test digit
- The digit just to the right of the rounding digit, used to decide rounding direction.
Rules to remember
- If the test digit is 5 or more, round the rounding digit up by 1.
- If the test digit is less than 5, keep the rounding digit the same.
- All digits to the right of the rounding digit become 0.
Step by step
- 1Find the placeUnderline the digit in the place you're rounding to.
- 2Check the next digitLook at the digit right after it.
- 3Round up or keep5 or more rounds up; less than 5 stays the same. Replace remaining digits with 0.
Common mistakes
- Rounding based on the wrong digit.
- Forgetting to zero out digits after the rounding place.
Tips
- Circle the test digit before deciding to remind yourself which one matters.