Expanded form: Writing a number as the sum of the value of each digit based on its place value
Note: Each digit represents its value multiplied by its place value position (ones, tens, hundreds).
- Step 1: Identify the place value of each digit
- Step 2: Multiply each digit by its place value
- Step 3: Write the number as the sum of these values
2 is in the hundreds place (2 × 100)
3 is in the tens place (3 × 10)
4 is in the ones place (4 × 1)
2 × 100 = 200
3 × 10 = 30
4 × 1 = 4
234 = 200 + 30 + 4
200 + 30 + 4 = 234 ✓
234 = 200 + 30 + 4
• Place value system: Each position represents a power of 10
• Digit multiplication: Multiply each digit by its positional value
• Summation: The expanded form adds up to the original number
• Practice Tip: Always verify by adding the expanded parts to check if you get the original number
- 145 = 100 + 40 + 5
- 367 = 300 + 60 + 7
- 509 = 500 + 0 + 9
- Start from the leftmost digit (highest place value)
- Remember that 0 in any place contributes 0 to the sum
- Use base-10 blocks or visual aids to understand place value
Q: What if there's a zero in the tens place?
A: Include it in the expanded form: 205 = 200 + 0 + 5 (or 200 + 5).
Q: Can I write expanded form differently?
A: Yes, another way is: 234 = (2 × 100) + (3 × 10) + (4 × 1).
Place value: The value of a digit based on its position in the number (ones, tens, hundreds)
Note: Each position in a number has a specific value that is 10 times the value of the position to its right.
- Step 1: Identify the position of each digit (hundreds, tens, ones)
- Step 2: Determine the place value multiplier (100, 10, 1)
- Step 3: Multiply each digit by its place value
4 is in the hundreds place
7 is in the tens place
2 is in the ones place
Hundreds place: ×100
Tens place: ×10
Ones place: ×1
4 × 100 = 400
7 × 10 = 70
2 × 1 = 2
400 + 70 + 2 = 472 ✓
In 472: 4 has a value of 400, 7 has a value of 70, and 2 has a value of 2
• Positional value: Each digit's value depends on its position
• Base-10 system: Each position is 10 times the previous position
• Place value multiplication: Multiply digit by position value
• Practice Tip: Count by hundreds, tens, and ones to verify your identification
- 358: 3=300, 5=50, 8=8
- 194: 1=100, 9=90, 4=4
- 607: 6=600, 0=0, 7=7
- Read the number aloud to identify place values
- Think of the number in groups: "four hundred seventy-two"
- Draw place value charts to visualize the breakdown
Q: What if the number has a zero in the ones place?
A: Include the zero: 370: 3=300, 7=70, 0=0.
Q: Can I decompose numbers in other ways?
A: Yes, expanded form is one way. Other ways include word form and standard form.
Standard to expanded conversion: Changing a number from its normal written form to showing each digit's place value contribution
Note: This conversion helps understand the actual value each digit contributes to the total number.
- Step 1: Separate each digit based on its position
- Step 2: Assign the appropriate place value (hundreds, tens, ones)
- Step 3: Express each digit as its value times its place value
- Step 4: Write as a sum of all place values
5 is in the hundreds place
8 is in the tens place
3 is in the ones place
5 × 100 = 500
8 × 10 = 80
3 × 1 = 3
583 = 500 + 80 + 3
500 + 80 + 3 = 583 ✓
583 = 500 + 80 + 3
• Place value system: Each position represents a power of 10
• Digit multiplication: Multiply each digit by its positional value
• Summation: The expanded form adds up to the original number
• Practice Tip: Think of the number as "five hundred eighty-three" to identify place values
- Standard to expanded: 437 = 400 + 30 + 7
- Alternative notation: 583 = (5 × 100) + (8 × 10) + (3 × 1)
- With zeros: 405 = 400 + 0 + 5
- Read the number in words to identify place values
- Always verify by adding the expanded parts
- Use base-10 blocks to visualize the conversion
Q: Can I skip zeros when writing expanded form?
A: Technically yes, but it's better to include them initially for learning: 502 = 500 + 0 + 2.
Q: Is expanded form useful in real life?
A: Yes, it helps with mental math, estimation, and understanding large numbers.
Expanded to standard conversion: Combining place value parts to form the standard written number
Note: This is the reverse of expanded form, where individual place values are added together to get the whole number.
- Step 1: Identify the hundreds value (600)
- Step 2: Identify the tens value (40)
- Step 3: Identify the ones value (7)
- Step 4: Add all values together to get the standard form
600 represents 6 hundreds
40 represents 4 tens
7 represents 7 ones
6 hundreds + 4 tens + 7 ones = 647
600 + 40 + 7 = 647
Check: 647 in expanded form = 600 + 40 + 7 ✓
647
• Addition: Combine all place values to get the whole number
• Place value: Each part contributes to a specific position in the final number
• Verification: Convert back to expanded form to check accuracy
• Practice Tip: Add from right to left (ones, tens, hundreds) for easier mental math
- 200 + 30 + 5 = 235
- 700 + 0 + 9 = 709
- 100 + 80 + 0 = 180
- Add from smallest to largest place values (ones, tens, hundreds)
- Align numbers vertically to avoid calculation errors
- Always verify by converting back to expanded form
Q: What if one place value is missing?
A: Treat it as zero. Example: 300 + 0 + 7 = 307.
Q: Can I add the parts in any order?
A: Yes, addition is commutative, but it's easier to go from right to left.
Missing place values: Finding the unknown value in an expanded form equation
Note: This requires understanding how place values contribute to the total number and using subtraction to find missing parts.
- Step 1: Identify the known place values (400 and 8)
- Step 2: Identify the total number (458)
- Step 3: Subtract the known values from the total to find the missing value
- Step 4: Verify the result by adding all parts
We have 400 (hundreds) and 8 (ones)
400 + 8 = 408
Total is 458, so: 458 - 408 = 50
400 + 50 + 8 = 458 ✓
The missing value is 50
• Subtraction: Use subtraction to find missing parts in addition equations
• Place value: Understand which position the missing value occupies
• Verification: Always check by adding all parts to confirm the total
• Practice Tip: Think about what number added to known parts gives the total
- 200 + ___ + 5 = 235, so ___ = 30
- ___ + 60 + 4 = 164, so ___ = 100
- 500 + 0 + ___ = 509, so ___ = 9
- First add all known values together
- Then subtract from the total to find the missing part
- Always verify your answer by completing the equation
Q: What if the missing value is in the hundreds place?
A: Same approach: subtract the known parts from the total. Example: ___ + 50 + 3 = 253, so ___ = 200.
Q: How do I know which place value is missing?
A: Look at the gaps in the place values: hundreds, tens, or ones.