Estimating is using rounded numbers to find an approximate sum, difference, product, or quotient of numbers. It makes working with numbers easier.
In this lesson, let's practice estimating money. 💵
Let's say you're at the grocery store. You want to know if the $20 you brought is enough to pay for your total bill.
Here are the prices of your items:
Let's estimate.
First, we round the prices to the nearest dollar.
We don't want to have cents in our prices because we're in a hurry to estimate.
Then, we add the rounded prices.
So the total bill is about $17.
This is not the exact total. Just an estimate.
Is the estimate close to the exact total?
Let's see. 📝
Our estimate of $17 is very close to the exact amount of $17.38.
Since you have $20, you have more than enough to pay for all the items in your cart.
$20 - $17 = $3
After paying, you'll have around $3 left.
That's not the exact change, but it's close enough.
A loaf of fresh white bread costs $3.85.
About how much do 8 loaves cost?
If you're in a hurry to know the total cost, then you can just estimate first.
First, we round $3.85 to the nearest dollar.
The target digit is 3.
The 8 to the right of the 3 tells us to round up.
This means we add 1 to 3, and drop the other digits to the right of the target.
$3 + 1 = $4
Now, it's easier to multiply.
$4 × 8 = $32
Our estimated total cost for 8 loaves is $32. ✅
Let's see what the exact total is:
Our estimate of $32 is close to the exact amount of $30.80.
Great job learning how to estimate money.
It's really just like estimating decimals.
Now, try the practice.