Login

How to Estimate Products

Instructor: Dana Sparkman
In multiplication problems, sometimes we want to get an answer that is 'close enough,' not exact. In this lesson, you will learn how to estimate products to get a 'close enough' answer.

Estimating Products

There are two skills needed for estimating products: rounding and multiplying with zeroes. Let's take a closer look at these skills now.

Rounding

When we round numbers, we adjust them so that they are more 'friendly,' or easier to use when calculating.

We can round to the nearest ten, the nearest hundred, and so on. When rounding to the nearest ten, for example, look at the number to the right of the tens place. If it is 5 or greater, raise the number in the tens place by one digit, and change the number in the ones place to zero. If it is less than 5, leave the number in the tens place as it is, and change the number in the ones place to zero.

Example 1: 78

The number to the right of the tens place is 8. Because 8 is greater than 5, raise the number in the tens place - 7 - up to 8, and change the number in the ones place to zero. So, 78 rounds to 80.

Example 2: 437

Here, we will round to the nearest hundred. Look at the number to the right of the hundreds place (in this case, 3). Because 3 is less than 5, keep the number in the hundreds place at 4, and change the other digits to zeroes. So, 437 rounds to 400.

Multiplying with Zeroes

To multiply numbers with zeroes, first multiply the non-zero numbers together. Then, write the number of zeroes you see in the problem on the end of the answer.

Example 1: 80 x 30

Multiply the non-zero numbers: 8 x 3 = 24

Write the number of zeroes you see on the end of the answer. Here, there are two zeroes, so the answer becomes 2,400.

Example 2: 40 x 700

Multiply the non-zero numbers: 4 x 7 = 28

Write the number of zeroes you see on the end of the answer. Here, there are three zeroes, so the answer becomes 28,000.

Estimating Products

Step 1: Round 2 and 3 digit numbers to the nearest ten or hundred. Do not round one-digit numbers.

Step 2: Multiply the non-zero digits.

Step 3: Write the number of zeroes in the rounded numbers on the end of the answer.

Example 1:

7 x 58 = ?

7 is a one-digit number, so do not round.

Round 58 to the nearest ten. Because the number in the ones place is five or greater, round up to 60.

7 x 60 = ?

Multiply the non-zero digits: 7 x 6 = 42

To unlock this lesson you must be a Study.com Member.
Create your account

Register for a free trial

Are you a student or a teacher?
I am a teacher
What is your educational goal?
 Back

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back

Earning College Credit

Did you know… We have over 95 college courses that prepare you to earn credit by exam that is accepted by over 2,000 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it free for 5 days!
Create An Account
Support