In the last few lessons, you mastered adding, subtracting, multiplying, and dividing decimals.
Now, let's try solving real world problems with decimals.
You'll find decimals in:
- prices of items
- temperatures
- weights of objects
- volumes of liquids
- lengths of household items, and more.
So in this lesson, let's solve a few real life decimal problems together.
Imagine shopping for toys. You pick out toys that cost $29.95, $42.30, and $98.15. How much do you have to pay for all three toys?
The problem is asking us to add three prices.
Let's write an equation to help solve the problem:
$29.95 + $42.30 + $98.15 = ?
What's the sum of these numbers? Tip: use column form.
Yes, it's $170.40.
Lastly, we write a complete sentence to show our answer.
I have to pay $170.40 for all three toys.
It's important to write the dollar sign to show that we're talking about money.
Let's solve another problem together.
Marie is sewing curtains for the school play. She needs a total of 276.35 ft of fabric. Right now, she has a piece of fabric that's 68.2 ft long. She has another piece of fabric that's 45.8 ft long. How much more fabric does Marie need to buy?
We need to use two operations to solve this problem.
Step 1. Add the length of the two fabrics that Marie already has.
45.8 + 68.2 = 114
Step 2. Subtract the answer in Step 1 from the total length of fabric needed.
The equation for the second step is:
276.35 - 114 = 162.35
Now, let's write our answer as a complete sentence, so people know what we're talking about.
Marie needs to buy 162.35 more feet of fabric.
Note: Always include the unit of measure in your final answer.
Kim runs 6.75 miles every day. How many miles does Kim run in 5 days?
The question is telling us to find the total miles that Kim ran in 5 days.
The bar model for this problem looks like:
This shows us that we need to multiply.
We can write an equation based on the bar model:
6.75 × 5 = ?
Let's find the product using column form.
Finally, we write a complete sentence for our answer.
Kim ran 33.75 miles in 5 days.
Great work.
Sam put in the same amount of money in his piggy bank every day. If at the end of 30 days he saved $238.50, how much money did he put in each day?
A bar model for this problem looks like this:
First, write an equation for it.
238.50 ÷ 30 = ?
Next, solve the problem with long division.
Tip: Jump back to the lessons on long division if you can't remember how to do that.
Finally, write a complete sentence for your answer.
Sam put in $7.95 in his piggy bank each day.
Great job learning how to solve decimal word problems. 👏
Try solving decimal word problems on your own in the practice. Practice helps you improve your math skills.