How to Estimate Money

      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. 💵

Example 1

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.

Is Your Money Enough?

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.

Example 2: Cost of Bread

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.