Rounding Nearest 10 and 100 Worksheet for Grade 4 Students

Rounding nearest 10 and 100 worksheet: rounding rules, estimation, and number sense with step-by-step solutions.

Worksheet: Exercises 1-3
1 Rounding to Nearest 10
Exercise 1: Rounding to Nearest 10
Round to the nearest 10: 23, 47, 55, 89
Definition:

Rounding to nearest 10: Finding the closest multiple of 10 to a given number.

Method:
  1. Look at the ones digit
  2. If ones digit is 0, 1, 2, 3, or 4 → round down
  3. If ones digit is 5, 6, 7, 8, or 9 → round up
  4. Change the ones digit to 0
Examples
23→20, 47→50, 55→60, 89→90
Step 1: Analyze 23

Ones digit is 3 → 3<5 → round down → 23→20

Step 2: Analyze 47

Ones digit is 7 → 7≥5 → round up → 47→50

Step 3: Analyze 55

Ones digit is 5 → 5≥5 → round up → 55→60

Step 4: Analyze 89

Ones digit is 9 → 9≥5 → round up → 89→90

23→20, 47→50, 55→60, 89→90
Final answer:

23→20, 47→50, 55→60, 89→90

Applied rules:

• Rounding rule: Look at ones digit to decide up/down

• Round down: 0,1,2,3,4 → change ones to 0

• Round up: 5,6,7,8,9 → add 1 to tens, change ones to 0

2 Rounding to Nearest 100
Exercise 2: Rounding to Nearest 100
Round to the nearest 100: 147, 250, 365, 499
Definition:

Rounding to nearest 100: Finding the closest multiple of 100 to a given number.

Examples
147→100, 250→300, 365→400, 499→500
Step 1: Analyze 147

Look at tens digit (4) → 4<5 → round down → 147→100

Step 2: Analyze 250

Look at tens digit (5) → 5≥5 → round up → 250→300

Step 3: Analyze 365

Look at tens digit (6) → 6≥5 → round up → 365→400

Step 4: Analyze 499

Look at tens digit (9) → 9≥5 → round up → 499→500

147→100, 250→300, 365→400, 499→500
Final answer:

147→100, 250→300, 365→400, 499→500

Applied rules:

• Rounding rule: Look at tens digit to decide up/down

• Round down: 0,1,2,3,4 → change tens and ones to 0

• Round up: 5,6,7,8,9 → add 1 to hundreds, change tens and ones to 0

3 Mixed Rounding Practice
Exercise 3: Mixed Rounding Practice
Round to nearest 10: 67, 84, 95; Round to nearest 100: 178, 345, 555
Definition:

Mixed rounding: Practicing both rounding to nearest 10 and 100.

Nearest 10
67→70, 84→80, 95→100
Nearest 100
178→200, 345→300, 555→600
Step 1: Round 67 to nearest 10

Ones digit is 7 → 7≥5 → round up → 67→70

Step 2: Round 178 to nearest 100

Tens digit is 7 → 7≥5 → round up → 178→200

Step 3: Round 84 to nearest 10

Ones digit is 4 → 4<5 → round down → 84→80

Step 4: Round 345 to nearest 100

Tens digit is 4 → 4<5 → round down → 345→300

67→70, 84→80, 95→100, 178→200, 345→300, 555→600
Final answer:

Mixed rounding: 67→70, 84→80, 95→100, 178→200, 345→300, 555→600

Applied rules:

• Nearest 10: Look at ones digit

• Nearest 100: Look at tens digit

• Consistency: Apply same rules regardless of target

Rounding Rules and Methods
X → Y (rounded to nearest Z)
Rounding Formula
To Nearest 10
Look at ones digit
0-4: down, 5-9: up
To Nearest 100
Look at tens digit
0-4: down, 5-9: up
Rounding Rule
≥5 up, <5 down
Universal principle
Key definitions:

Rounding: Replacing a number with an approximate value that has a simpler representation

Estimation: Finding an approximate answer using rounded numbers

Nearest 10: Rounding to the closest multiple of 10

Nearest 100: Rounding to the closest multiple of 100

Complete methodology:
  1. Identify target place: Determine if rounding to 10 or 100
  2. Find decision digit: Look at ones digit (for 10) or tens digit (for 100)
  3. Apply rule: If digit ≥ 5 round up, if digit < 5 round down
  4. Adjust number: Change appropriate digits to 0, add 1 if rounding up
Tip 1: For nearest 10, look at ones digit; for nearest 100, look at tens digit.
Tip 2: Remember: 5 rounds up (5, 6, 7, 8, 9 all round up).
Tip 3: When rounding up, add 1 to the target place value.
Tip 4: Always check if your rounded number is reasonable.
Common errors: Looking at wrong digit, confusing rounding up/down, forgetting to change digits to 0.
Key concepts: The decision digit determines direction, all digits to the right become 0.
Formulas to know by heart:

• Rounding rule: If decision digit ≥ 5, round up; if < 5, round down

• To nearest 10: Look at ones digit

• To nearest 100: Look at tens digit

• Adjustment: Change digits to the right of target to 0

Worksheet: Exercises 4-5
4 Word Problems
Exercise 4: Word Problems
Sarah has 247 stickers. Round this number to the nearest 10 and nearest 100.
Definition:

Word problems: Applying rounding to real-life situations.

Nearest 10
247 → 250
Nearest 100
247 → 200
Step 1: Round to nearest 10

Ones digit is 7 → 7≥5 → round up → 247→250

Step 2: Round to nearest 100

Tens digit is 4 → 4<5 → round down → 247→200

Step 3: Verify

250 is closer to 247 than 240; 200 is closer to 247 than 300

Nearest 10: 250, Nearest 100: 200
Final answer:

Sarah has approximately 250 stickers (nearest 10) or 200 stickers (nearest 100)

Applied rules:

• Context: Apply rounding to real-world scenarios

• Verification: Check that rounded number is reasonable

• Multiple targets: Can round to different place values

5 Estimation Practice
Exercise 5: Estimation Practice
Estimate 347 + 289 by rounding each number to the nearest 100.
Definition:

Estimation: Using rounded numbers to get an approximate answer.

Round first number
347 → 300
Round second number
289 → 300
Add rounded numbers
300 + 300 = 600
Step 1: Round 347 to nearest 100

Tens digit is 4 → 4<5 → round down → 347→300

Step 2: Round 289 to nearest 100

Tens digit is 8 → 8≥5 → round up → 289→300

Step 3: Add rounded numbers

300 + 300 = 600

Step 4: Compare with exact answer

Exact: 347 + 289 = 636; Estimate: 600 (reasonably close)

Estimated sum: 600
Final answer:

347 + 289 ≈ 600 (estimated)

Applied rules:

• Estimation: Round first, then calculate

• Reasonableness: Check that estimate is close to exact answer

• Simplification: Makes complex calculations easier

Complete Worksheet Guide: Rounding to 10 and 100
X → Y (rounded to nearest Z)
Rounding Formula
Key definitions:

Rounding: Replacing a number with an approximate value that has a simpler representation

Estimation: Finding an approximate answer using rounded numbers

Nearest 10: Rounding to the closest multiple of 10

Nearest 100: Rounding to the closest multiple of 100

Complete methodology:
  1. Identify target place: Determine if rounding to 10 or 100
  2. Find decision digit: Look at ones digit (for 10) or tens digit (for 100)
  3. Apply rule: If digit ≥ 5 round up, if digit < 5 round down
  4. Adjust number: Change appropriate digits to 0, add 1 if rounding up
Tip 1: For nearest 10, look at ones digit; for nearest 100, look at tens digit.
Tip 2: Remember: 5 rounds up (5, 6, 7, 8, 9 all round up).
Tip 3: When rounding up, add 1 to the target place value.
Tip 4: Always check if your rounded number is reasonable.
Common errors: Looking at wrong digit, confusing rounding up/down, forgetting to change digits to 0.
Key concepts: The decision digit determines direction, all digits to the right become 0.
Formulas to know by heart:

• Rounding rule: If decision digit ≥ 5, round up; if < 5, round down

• To nearest 10: Look at ones digit

• To nearest 100: Look at tens digit

• Adjustment: Change digits to the right of target to 0

Rounding Patterns and Rules
Rounding Patterns
Rounding patterns:
To nearest 10: 0-4 round down, 5-9 round up
To nearest 100: 0-4 round down, 5-9 round up
Decision digits: ones (10), tens (100)

Rounding Patterns:

  • 0-4: Round down
  • 5-9: Round up
  • Decision digit determines direction
  • Target place value changes

Questions & Answers

Question: Why do we round 5 up instead of down? It's right in the middle!

Answer: That's a great question! You're right that 5 is in the middle, but mathematicians agreed to always round 5 up to make the rules consistent:

  • It creates a simple, consistent rule: numbers 5-9 always round up
  • It prevents bias in calculations (if we alternated, it could skew results)
  • It makes the rule easier to remember: 5 and above round up, below 5 round down

This agreement helps ensure everyone gets the same answer when rounding!

Question: My child is getting confused about which digit to look at when rounding. How can I help?

Answer: Here are helpful strategies to clarify which digit to look at:

  • For rounding to nearest 10: Look at the ones digit (rightmost digit)
  • For rounding to nearest 100: Look at the tens digit (second from right)
  • Use visual aids like place value charts to show positions
  • Practice with underlining or circling the decision digit
  • Remember: the decision digit is always one position to the right of the target place

With practice, your child will quickly recognize which digit determines the rounding direction.

Question: How can I help students understand when to round up versus down?

Answer: Effective strategies for understanding rounding direction:

  • Simple rule: 0, 1, 2, 3, 4 → round down; 5, 6, 7, 8, 9 → round up
  • Think of it as "going toward" the closer multiple
  • Use number lines to visualize which multiple is closer
  • Practice with real-world examples (prices, distances)
  • Create mnemonics like "5 and above, give it a shove" (round up)

The key is helping students internalize that 5 is the halfway point, so it goes up by convention.