Carrying (Regrouping): When adding digits in a place value column results in a number 10 or greater, carry the tens digit to the next higher place value
- Align numbers by place value (ones under ones, tens under tens)
- Start adding from the rightmost place (ones)
- If sum ≥ 10, write the ones digit and carry the tens digit to next place
- Continue to the left
Carry 1 to tens place: 7 + 8 = 15
\(7 + 8 = 15\)
Since 15 ≥ 10, write 5 in ones place and carry 1 to tens place
\(4 + 2 + 1\) (carried) = 7
Tens: 7, Ones: 5
\(47 + 28 = 75\)
• Carrying: When sum ≥ 10, carry the tens digit to next place
• Place value: Each place represents a power of 10
• Addition: Always add digits in the same place value column
Multiple carrying: When adding across multiple place values, carry sequentially from right to left
Carry 1 from ones to tens (6+4=10), then carry 1 from tens to hundreds (5+8+1=14)
\(6 + 4 = 10\)
Write 0 in ones place, carry 1 to tens place
\(5 + 8 + 1\) (carried) = 14
Write 4 in tens place, carry 1 to hundreds place
\(1 + 2 + 1\) (carried) = 4
Hundreds: 4, Tens: 4, Ones: 0
\(156 + 284 = 440\)
• Sequential carrying: Carry from right to left as needed
• Place value relationships: 10 ones = 1 ten, 10 tens = 1 hundred
• Systematic approach: Work from right to left, carrying as needed
Borrowing (Regrouping): When subtracting, if the top digit is smaller than the bottom digit, borrow 1 from the next higher place value
Borrowed 1 ten → 10 ones: 83 → 7^{13}
\(3 < 7\), so we cannot subtract: 3 - 7
Borrow 1 ten from 8 tens: 8 tens = 7 tens + 1 ten
Add the borrowed 1 ten to ones: 1 ten = 10 ones
New ones: 3 + 10 = 13 ones
\(13 - 7 = 6\)
\(7 - 2 = 5\)
\(83 - 27 = 56\)
• Regrouping: Borrow 1 from higher place value when needed
• Place value: 1 ten = 10 ones, 1 hundred = 10 tens
• Subtraction: Always subtract bottom number from top number
Carrying: Moving a group of 10 from one place value to the next higher place value in addition
Borrowing: Taking from a higher place value to add to a lower place value in subtraction
Regrouping: Converting between place values to enable operations
Place value: The value of a digit based on its position in the number
- Align numbers: Match digits by place value
- Identify operation: Determine if addition or subtraction
- Start from right: Begin with the ones place
- Check for carrying/borrowing: If needed, apply appropriate operation
- Add each place: Continue working left until all places are done
• Carrying condition: When sum ≥ 10, carry the tens digit
• Borrowing condition: When top digit < bottom digit
• Place value relationships: 10 ones = 1 ten, 10 tens = 1 hundred
• Inclusion rule: Always include carried digit in next place value addition
• Reduction rule: When borrowing, reduce the higher place value by 1
• Verification: Estimate to check if answer is reasonable
Mixed carrying: When some places require carrying while others don't, handle each place individually
Carry 1 from ones to tens: 3 + 7 = 10
\(3 + 7 = 10\)
Write 0 in ones place, carry 1 to tens place
\(8 + 4 + 1\) (carried) = 13
Write 3 in tens place, carry 1 to hundreds place
\(5 + 2 + 1\) (carried) = 8
Hundreds: 8, Tens: 3, Ones: 0
\(583 + 247 = 830\)
• Selective carrying: Only carry when sum ≥ 10 for each specific place
• Sequential processing: Handle carrying one place at a time
• Verification: Check by estimating: 583 ≈ 580, 247 ≈ 250, 580 + 250 = 830 ✓
Multiple borrowing: When subtracting across multiple place values, borrow sequentially from left to right
Borrowed 1 hundred → 10 tens → 9 tens + 1 ten → 10 ones
\(5 < 7\), so we cannot subtract: 5 - 7
Tens place has 0, so we cannot borrow from tens
Borrow 1 hundred from 4 hundreds: 4 hundreds = 3 hundreds + 1 hundred
Add the borrowed 1 hundred to tens: 1 hundred = 10 tens
New tens: 0 + 10 = 10 tens
Take 1 ten from 10 tens: 10 tens = 9 tens + 1 ten
Add the borrowed 1 ten to ones: 1 ten = 10 ones
New ones: 5 + 10 = 15 ones
Ones: \(15 - 7 = 8\)
Tens: \(9 - 8 = 1\)
Hundreds: \(3 - 1 = 2\)
\(405 - 187 = 218\)
• Sequential borrowing: When lower place has 0, borrow from higher place first
• Place value relationships: 1 hundred = 10 tens, 1 ten = 10 ones
• Systematic approach: Work from right to left, borrowing as needed