Rounding Numbers

For Elementary Students

What Is Rounding?

Rounding means changing a number to a nearby number that's easier to work with.

Think about it like this: If you have 48 candies, you might say "about 50 candies" because 50 is easier to remember and say!

Why Do We Round?

Rounding makes numbers simpler!

Examples:

• "The movie theater has 487 seats" → "about 500 seats"
• "I have 23 stickers" → "about 20 stickers"
• "The book costs $9.95" → "about $10"

The Rounding Rule (Simple Version)

Look at the next digit:

• If it's 5 or more → round UP ⬆️
• If it's 4 or less → round DOWN ⬇️ (stay the same)

Memory trick: "5 or more, raise the score. 4 or less, let it rest!"

Rounding to the Nearest Ten

Example: Round 47 to the nearest ten

Step 1: What tens is 47 between?

40        47        50
├─────────●─────────┤

47 is between 40 and 50.

Step 2: Look at the ones digit: 7

7 is 5 or more, so round UP to 50!

Answer: 50

Another Example

Round 32 to the nearest ten

30        32        40
├───●─────────────────┤

32 is between 30 and 40.

Ones digit: 2 (less than 5) → round DOWN to 30

Answer: 30

The Middle Number (When It's Exactly 5)

Example: Round 25 to the nearest ten

20        25        30
├─────────●─────────┤

25 is exactly in the middle!

Rule: When the digit is exactly 5, we round UP!

Answer: 30

For Junior High Students

The Rounding Process

Steps to round any number:

1. Find the digit in the place you're rounding to
2. Look at the digit one place to the right
3. If that digit is 5 or more → round up (add 1)
4. If that digit is 4 or less → round down (keep the same)
5. Replace all digits to the right with zeros

Rounding to the Nearest Ten

Example: Round 47 to the nearest ten

• Rounding place: Tens digit = 4
• Look right: Ones digit = 7 (5 or more)
• Action: Round up! 4 becomes 5
• Answer: 50

Example: Round 132 to the nearest ten

• Tens digit: 3
• Ones digit: 2 (less than 5)
• Action: Stay the same
• Answer: 130

Rounding to the Nearest Hundred

Example: Round 867 to the nearest hundred

• Hundreds digit: 8
• Tens digit: 6 (5 or more)
• Action: Round up! 8 becomes 9
• Answer: 900

Example: Round 342 to the nearest hundred

• Hundreds digit: 3
• Tens digit: 4 (less than 5)
• Action: Stay the same
• Answer: 300

Rounding to the Nearest Thousand

Example: Round 4,389 to the nearest thousand

• Thousands digit: 4
• Hundreds digit: 3 (less than 5)
• Action: Stay the same
• Answer: 4,000

Example: Round 7,652 to the nearest thousand

• Thousands digit: 7
• Hundreds digit: 6 (5 or more)
• Action: Round up! 7 becomes 8
• Answer: 8,000

Rounding Decimals

The same rules apply to decimals!

Example: Round 3.847 to the nearest tenth

• Tenths place: 8
• Look right (hundredths): 4 (less than 5)
• Action: Stay the same
• Answer: 3.8

Example: Round 6.75 to the nearest tenth

• Tenths place: 7
• Look right (hundredths): 5 (5 or more)
• Action: Round up! 7 becomes 8
• Answer: 6.8

Rounding to the Nearest Whole Number

Example: Round 8.3 to the nearest whole number

• Ones place: 8
• Tenths place: 3 (less than 5)
• Answer: 8

Example: Round 5.7 to the nearest whole number

• Ones place: 5
• Tenths place: 7 (5 or more)
• Answer: 6

Multiple Rounding Steps

Be careful! Round only once, directly to the target place.

Wrong way:

• Round 4.748 to hundredths: 4.75
• Then round to tenths: 4.8 ❌

Right way:

• Round 4.748 directly to tenths
• Look at hundredths (4)
• Answer: 4.7 ✓

Using Rounding for Estimation

Example: Estimate 48 + 32

Round both:

• 48 → 50
• 32 → 30

Estimate: 50 + 30 = 80

Actual: 48 + 32 = 80 (very close!)

Rounding in Real Life

Shopping: "These shoes cost $79.99" → "about $80"

Population: "City has 248,517 people" → "about 250,000 people"

Distance: "Drive is 147 miles" → "about 150 miles"

Temperature: "It's 72.4 degrees" → "about 72 degrees"

Why Rounding Matters

✓ Makes mental math easier

✓ Helps you estimate quickly

✓ Makes numbers easier to remember and communicate

✓ Good for checking if answers are reasonable

Important Notes

Rounding is an approximation — the rounded number is close but not exact.

When NOT to round:

• Exact calculations (money, measurements in building)
• Scientific precision
• When accuracy is critical

Practice