rounding multi-digit whole numbers

Rounding Multi-Digit Whole Numbers

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In grade 3, children familiarize themselves a bit with rounding a given number to the closest 10 or 100 by applying their place value knowledge.

In grade 4, they start learning the benefits of rounding to any place value and become comfortable with rounding multi-digit whole numbers to the nearest thousand, ten thousand, or hundred thousand.

Math teachers can sometimes find themselves wondering how to facilitate this transition from rounding smaller numbers to rounding bigger numbers. The tips in this article will help guide you through this process.

What Is Rounding Multi-Digit Whole Numbers?

Start off by explaining to students what rounding a multi-digit number means. While most should already have an idea, it’s always a good idea to briefly review previously acquired knowledge.

Remind students that rounding means changing a number to make it easier to use, despite the new number not being as accurate. In other words, rounding means making a number simpler but still keeping its value close to the initial value.

Why Is Rounding Multi-Digit Whole Numbers Important?

You could start by engaging your students and asking them why there is a need to do rounding in the first place. Explain that rounding is a process that makes calculations easier – we change a given number to the nearest 10, 100, 1,000, 10,000, 100,000, etc. to be able to calculate more easily.

You can also provide students with some real-life examples. For instance, ask students to imagine they’re out shopping for new clothes in their favorite mall. Let’s say they see shoes from one brand that cost $4,799, then another brand has shoes they also like for $3,734, and a third one for $4,862.

Instead of remembering all of these digits when trying to make a decision, you may find it much easier to round the numbers to the nearest thousands. You’d then remember that two brands had shoes for approximately $5,000, and another brand had shoes for approximately $4,000.

Now that’s way easier, right?

clothes

How to Round Multi-Digit Whole Numbers?

Review Place Value

Before jumping into rounding multi-digit numbers to any place, polish up students’ knowledge on place value. This is a concept they’ve already learned and should be able to apply with ease if they wish to round whole multi-digit numbers.

Remind students that place value is the value of each digit in a specific number, that is, the value of where a digit is in a specific number. Feel free to check out our guide on how to teach place value to 4th graders if children need to review this concept in more detail.

Rounding Multi-Digit Whole Numbers

Give students a few examples, and make sure to start with easier examples, such as two-digit or three-digit numbers. For instance:

12 rounded to the nearest number is 10, because 12 is closer to 10 than to 20. We can thus say that we are rounding down 12.

Use this simple rhyme to explain to students how to round numbers to the nearest place value:

If it’s four or less, give it a rest. If it’s five or more, raise the score!

However, make sure to highlight that they should look at the place value below the place value they’re rounding to. In other words, students should look at:

  • ones place value to round to the nearest ten
  • tens place value to round to the nearest hundred
  • hundreds place value to round to the nearest thousand etc.

For example, explain that if they’re trying to round 3, 523 to the nearest thousand, we’ll look at the hundreds place. We see that the hundreds place has a value of 5, so we use our rhyme and we round up to 4,000 (“we raise the score”).

Explain that if we’re trying to round 2,435 to the nearest thousand, we’ll notice that the hundreds place has a value of 4 (“if it’s four or less, we give it a rest”), so we simply round down to 2,000.

Number Line Activity

Probably the best way to teach how to round multi-digit whole numbers is to use a number line. This way, children can visualize the process of rounding numbers. Use the number line from this worksheet. Print out pages 6-12 from the worksheet and distribute it to each student.

Explain to students that you’re going to use benchmark numbers on the number line in order to help you with the number rounding. For instance, let’s say you’re trying to round 928 to the nearest hundred. The benchmark numbers, in this case, would be 900 (to the left) and 1,000 (to the right).

You may also want to create a big, colorful number line on the whiteboard to further practice. Prepare several math problems related to rounding multi-digit numbers in advance and hand them out to the children. Ask them to present them on their number line and to explain how they managed to round the given number.

For instance, ask them to round the number 43,708 to the nearest thousand. They should first identify the benchmark numbers and place them on the number line, which in this case, would be 43,000 and 44,000.

Next, students could explain they’re using the rhyme, keeping in mind that they look at the place value below the place value they’re rounding to. That is, they’re looking at the hundreds place or 7 in 43,708. This is why they round up to 44,000!

Before You Leave…

Make sure to check out our worksheets and resources on teaching rounding multi-digit whole numbers. These are all pdf files, so you’ll be able to print them out easily:

To get the Editable versions of these files, join us in the Math Teacher Coach community!

This article is based on:

Unit 1 – Place Value and Rounding of Multi-Digit Whole Numbers

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