If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

### Course: Arithmetic>Unit 12

Lesson 3: Subtracting decimals intro

# Estimating decimal subtraction

This video is all about learning to estimate when subtracting decimals. It emphasizes the importance of rounding to the nearest whole number and doing quick mental calculations to get an approximate answer. It's all about getting comfortable with estimation!

## Want to join the conversation?

• but how do you know if you round up or down?
• You look on the digit on the right of the one you're rounding. If that digit is 5, 6, 7, 8 or 9 you round up. If it's 0, 1, 2, 3, 4 you round down.

That's all, hope that helps.
• Thank you for helping a lot it was really easy after I learned
• arwe you lock?
(1 vote)
• bruh this stuff hard no cap.
• wow I now understand
• hi how do you know when to round
• You will know when to round when the question tells you or not. 'Basically rounding is if the given number or calculated number ending with a 1,2,3 or 4 you round down. Though if the given number or calculated number ends with 5,6,7,8 or 9 you round up.'

Hope this helps!
• how do u subtract 7.7 from 3.11? it doesn't explain here
(1 vote)
• Since 3.11 has two decimal points, and 7.7 has one, you can add a 0 at the end of 7.7 to make 7.70. With that, you can simply just flip the terms to make the equation 7.70 - 3.11, where you subtract 3.11 from 7.70 which is equal to 4.59. However, subtracting 7.70 from 3.11 will not result in a positive number. As a result, you will add a negative sign in front of your number, to get your solution of - 4.59 (negative 4.59).
• Anyone who got it right is a true king, i think that you all deserve a rest after this