Idea 6of 23Builds onPick the way that fits
Estimate a total by rounding
How can you tell roughly what three things cost, in your head?
Today you'll discover
- how to round a price to the nearest dollar
- how to add the rounded prices
- how an estimate checks the exact total
Think firstA book, a binder and paint
About how much do all three cost together?
Decide first, then press Next. Round each price before you add.
A receipt: a book $3.95, a binder $6.10 and paint $2.89, with question marks in the cost column. A column of estimates appears: about $4, $6 and $3, about $13 in all. Then the exact costs and the total, $12.94, and a line saying it is close to the estimate. The last step shows camp gear at $8.95, $14.10 and $5.98.
See the whole ideathe big idea and the key word, in one place
The big idea
To estimate a total, round each price to the nearest dollar, then add.
Why estimate?Before the till: do I have enough money? After the till: is the total about right? An estimate answers both in seconds.
Easy to get wrongDon't just cut off the cents. $2.89 is nearer $3 than $2, so it rounds up.
Key word
- estimate
- a number close to the exact answer, worked out quickly, often by rounding
Ready to use it?
- Estimate a total by rounding each price.
- Check an exact total against the estimate.