Show how many tens and ones are in 47.
Expanded form: Writing a number as the sum of its place values. For 2-digit numbers: tens + ones
- Identify the digit in the tens place
- Identify the digit in the ones place
- Write the tens value as (digit × 10)
- Write the ones value as (digit × 1)
- Add them together
In 47: TENS = 4, ONES = 7
4 tens = 4 × 10 = 40
7 ones = 7 × 1 = 7
47 = 40 + 7
47 in expanded form is 40 + 7
47 has 4 tens and 7 ones
• Place value rule: Each digit's value depends on its position
• Expanded form rule: Add the values of each place
• Tens rule: Tens digit × 10 gives the tens value
• Ones rule: Ones digit × 1 gives the ones value
Break down 83 into tens and ones.
Number decomposition: Breaking a number into its component parts based on place value
In 83: TENS = 8, ONES = 3
8 tens = 8 × 10 = 80
3 ones = 3 × 1 = 3
83 = 80 + 3
83 in expanded form is 80 + 3
83 has 8 tens and 3 ones
• Place value identification: Leftmost digit is tens, rightmost is ones
• Value calculation: Tens × 10, Ones × 1
• Addition principle: Combine place values with addition
Show the relationship between digits and their values.
Place value relationship: The position of a digit determines its actual value in the number
In 56: TENS = 5, ONES = 6
5 tens = 5 × 10 = 50
6 ones = 6 × 1 = 6
56 = 50 + 6
56 in expanded form is 50 + 6
56 has 5 tens and 6 ones
• Position matters: Tens place is worth 10 times the digit
• Ones place: Digit value equals itself
• Summation: Total value is the sum of all place values
Place value: The value of a digit based on its position in a number
Expanded form: Writing a number as the sum of its place values
Tens: The leftmost digit in a 2-digit number, worth 10 times its face value
Ones: The rightmost digit in a 2-digit number, worth its face value
- Identify positions: Recognize tens and ones places
- Extract digits: Separate the tens digit and ones digit
- Calculate values: Multiply tens by 10, ones by 1
- Write expanded form: Express as sum of place values
• Left digit: Always represents tens in 2-digit numbers
• Right digit: Always represents ones in 2-digit numbers
• Value calculation: Tens digit × 10, Ones digit × 1
• Expanded form: Sum of calculated place values
• Verification: Adding expanded parts should equal original number
Show how 92 is composed of tens and ones.
Number composition: Understanding how digits combine to form a whole number
In 92: TENS = 9, ONES = 2
9 tens = 9 × 10 = 90
2 ones = 2 × 1 = 2
92 = 90 + 2
92 in expanded form is 90 + 2
92 has 9 tens and 2 ones
• Position identification: Leftmost digit is tens place
• Value multiplication: Tens digit multiplied by 10
• Summation: Add place values to form expanded notation
Demonstrate complete understanding of place value.
Place value mastery: Understanding how each position contributes to the overall number value
In 38: TENS = 3, ONES = 8
3 tens = 3 × 10 = 30
8 ones = 8 × 1 = 8
38 = 30 + 8
38 in expanded form is 30 + 8
38 has 3 tens and 8 ones
• Place value recognition: Systematic identification of digit positions
• Value computation: Proper multiplication of digits by their place value
• Notation: Expressing as sum of individual place values
This comprehensive summary covers all aspects of expanded form for class 2 students, providing clear explanations, methods, and examples for mastering place value concepts.
Place Value: The value of a digit based on its position in a number. Each position has a different value.
Expanded Form: Writing a number as the sum of its place values (e.g., 47 = 40 + 7).
Tens Place: The leftmost position in a 2-digit number, worth 10 times the digit's face value.
Ones Place: The rightmost position in a 2-digit number, worth the digit's face value.
Digit: Any of the symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9 used to make numbers.
Position Rule: In a 2-digit number, the left digit is always the tens place and the right digit is always the ones place.
Value Rule: Tens digit × 10 = actual tens value; Ones digit × 1 = actual ones value.
Summation Rule: Expanded form is the sum of all place values.
Verification Rule: Adding expanded parts should equal the original number.
Consistency Rule: The same method works for any 2-digit number.
Method 1: Standard Approach
- Identify the tens digit (leftmost)
- Identify the ones digit (rightmost)
- Multiply tens digit by 10
- Multiply ones digit by 1
- Add the results together
Method 2: Verification Approach
- Write expanded form
- Add the expanded parts
- Check if result equals original number
Simple Examples:
23 = 20 + 3 (2 tens + 3 ones)
45 = 40 + 5 (4 tens + 5 ones)
Intermediate Examples:
67 = 60 + 7 (6 tens + 7 ones)
89 = 80 + 9 (8 tens + 9 ones)
Advanced Examples:
91 = 90 + 1 (9 tens + 1 one)
54 = 50 + 4 (5 tens + 4 ones)
Tips:
- Always multiply tens digit by 10
- Ones digit stays the same
- Check by adding expanded parts
Common Mistakes:
- Forgetting to multiply tens by 10
- Confusing tens and ones positions
- Omitting addition sign in expanded form
Memory Aids:
- "Tens are big!" - They multiply by 10
- "Ones stay small" - They stay as themselves
- "Left is tens, right is ones"
Quick Check: Always add expanded parts to verify your answer equals the original number.
Pattern Recognition: In expanded form, the first number is always a multiple of 10, the second is always less than 10.
Questions & Answers
Question: I don't understand why 47 becomes 40 + 7. Why isn't it just 4 + 7?
Answer: Great question! The key is understanding place value:
- In 47, the digit 4 is in the tens place, so it actually represents 4 groups of 10, which is 40
- In 47, the digit 7 is in the ones place, so it represents 7 individual units
- So 47 means 40 + 7, not 4 + 7
Think of it this way: If you have 47 apples, you could group them as 4 groups of 10 apples (40 apples) plus 7 individual apples. That's 40 + 7 = 47 apples total.
The position of each digit tells us its true value in the number!
Question: How do I know which digit is the tens and which is the ones?
Answer: It's easy once you know the pattern:
- Look at the number from left to right
- The first digit (leftmost) is always the tens place
- The second digit (rightmost) is always the ones place
Examples:
- In 25: 2 is tens, 5 is ones
- In 73: 7 is tens, 3 is ones
- In 91: 9 is tens, 1 is ones
Remember: Tens comes first (left side), Ones comes second (right side).
Question: What happens if I add the expanded form back together? Should I get the original number?
Answer: Yes, absolutely! This is a great way to check your work!
When you write a number in expanded form, you're just showing how it's made up of its parts. So when you add those parts back together, you should get the original number:
- 47 = 40 + 7 → 40 + 7 = 47 ✓
- 83 = 80 + 3 → 80 + 3 = 83 ✓
- 56 = 50 + 6 → 50 + 6 = 56 ✓
This is called the "check method" - always add your expanded parts to make sure they equal the original number. If they don't match, you made a mistake somewhere!
This helps you catch errors and confirms your understanding of place value.