4th Grade Rounding Whole Numbers Lesson: Notes and Examples (Free PDF)

Cover of the book Grade 4 Math Lessons (PDF)

Download as a PDFThe Grade 4 math lessons bookPrintable PDFSee the book ›

Sommaire

This 4th grade rounding lesson covers rounding whole numbers (Common Core 4.NBT.A.3), with a free PDF to print.

Key takeaway: This lesson helps fourth grade students round whole numbers to any place up to the hundred thousands.

Topic: Rounding Whole Numbers (4th grade)
Content: One-page lesson with a definition, a worked example and key facts
Standards: 4.NBT.A.3
Answers: Explanations included
Format: Free printable PDF, US Letter, black and white

Rounding replaces a number with the closest multiple of a place, such as ten, hundred, or thousand. Look at the digit to the right of that place. If it is 5 or more, round up. If it is 4 or less, keep the digit. Then change the digits to its right to zeros. Rounding also helps estimate sums and differences.

This lesson helps fourth grade students round whole numbers to any place up to the hundred thousands. It explains rounding as finding the nearest multiple of ten, hundred, or thousand, so the rule has a reason behind it.

Students learn to find the rounding place, to look at the digit to its right, and to use a number line to see which multiple is closer. They also meet the halfway case and numbers like 999 that carry into the next place. Also, plan about 20 minutes. Then, sketch a number line for each example, and mark the halfway point.

Grade 4 · Common Core State Standards: 4.NBT.A.3

Key facts in this 4th grade rounding lesson

Key facts

To round, look at the digit to the right of the place you want.
Digits 5, 6, 7, 8, and 9 round up. Digits 0, 1, 2, 3, and 4 round down.
A number exactly halfway between two multiples rounds up: 2,500 rounds to 3,000.
Then, a 9 can carry: 9,960 rounds to 10,000 at the nearest hundred.
To estimate, round every number to the same place, then add or subtract.

What does rounding mean?

Rounding swaps an exact number for a nearby, friendlier number. Newspapers say “about 19,000 fans” instead of “18,743 fans.” Rounding makes numbers easy to say, compare, and add in your head.

Rounding

To round a number to a place, find the closest multiple of that place. If a number is exactly halfway between two multiples, round up.

3,468 is closer to 3,500 than to 3,400, so it rounds to 3,500 (nearest hundred). The orange dot marks the halfway point, 3,450.

How do you round a whole number?

Three steps for rounding any whole number.

Underline the digit in the place you are rounding to.
Look at the digit to its right.
If that digit is 5 or more, add 1 to the underlined digit. If it is 4 or less, keep the underlined digit.
Change every digit to the right of the underlined place to 0.

Example: Round \(38,745\) to the nearest thousand. The underlined digit is 8 (thousands). Also, the digit to its right is 7, which is 5 or more, so 8 becomes 9. The answer is \(39,000\).

Does the place you pick change the answer?

Yes. A smaller place keeps more detail. A bigger place gives a rougher answer.

One number can be rounded to many places.

Watch for a 9. Rounding \(9,960\) to the nearest hundred gives \(10,000\), because 99 hundreds plus 1 more hundred is 100 hundreds.

How can rounding help you estimate?

To estimate a sum or a difference, round each number first, then add or subtract. Use the same place for every number so the problem is easy.

Rounding to the nearest thousand turns 4,862 + 2,139 into 5,000 + 2,000 = 7,000.

The exact sum is \(7,001\), which is close to the estimate of \(7,000\). If your exact answer is far from your estimate, check your work again.

4th grade rounding lesson: questions and answers

What is the rule for rounding up?

Round up when the digit to the right of the rounding place is 5 or more. Add 1 to the digit in the rounding place and change the digits to its right to zeros.

What does 2,500 round to at the nearest thousand?

It rounds to 3,000. The number is exactly halfway between 2,000 and 3,000, and the rule is to round halfway numbers up.

Why do we round numbers?

Rounded numbers are easier to compare and calculate in your head. They are good for estimates, such as checking that a total on a receipt makes sense.

How do you estimate a sum with rounding?

Round each number to the same place, then add. To estimate 4,862 + 2,139, round to the nearest thousand and add 5,000 + 2,000 = 7,000.

What happens when you round 999 to the nearest ten?

The answer is 1,000. The ones digit 9 rounds the 9 tens up to 10 tens, which carries into the hundreds and thousands.

Common mistakes with this 4th grade rounding lesson

Students look at the digit in the rounding place instead of the digit to its right. Underline the rounding place first, then check the next digit.
Students change every digit after the rounding place to a nine. Instead, replace each of those digits with a zero.
Students forget to carry when a nine rounds up. For example, 9,960 rounds up to 10,000 at the nearest hundred.

How to study this chapter

Draw a short number line between the two nearest multiples. Then mark the halfway point and place your number.
Underline the rounding place with one line and circle the next digit. This simple habit prevents most mistakes.
Parents can use prices or crowd counts from the news. Rounding real numbers shows why people use it.

Download the 4th grade rounding lesson as a PDF with the button below and keep it with your notes.