Addition and Subtraction of 4-Digit Numbers
"Add and subtract 4-digit numbers with regrouping and solve word problems."
A Today you'll learn
- Add 4-digit numbers with and without regrouping (carrying)
- Subtract 4-digit numbers with borrowing across zeros
- Solve two-step word problems involving real-life situations
B Let's understand
When adding and subtracting 4-digit numbers, always align the digits vertically according to their place values: Thousands under Thousands, Hundreds under Hundreds, Tens under Tens, and Ones under Ones. Always begin calculating from the Ones column and move leftward. In addition, when a column totals 10 or more, carry the 1 to the next place value. In subtraction, if the top digit is smaller than the bottom digit, borrow 1 from the next place on the left. When borrowing across zeros, borrow systematically from the nearest non-zero digit.
C See it step by step
- Ones: 8 + 4 = 12. Write 2, carry 1 to tens.
- Tens: 1 + 4 + 7 = 12. Write 2, carry 1 to hundreds.
- Hundreds: 1 + 6 + 5 = 12. Write 2, carry 1 to thousands.
- Thousands: 1 + 3 + 2 = 6. Write 6.
- Total sum = 6,222.
- Borrow across zeros: 5 thousands becomes 4 thousands, leaving 9 hundreds, 9 tens, and 10 ones.
- Ones: 10 - 6 = 4.
- Tens: 9 - 4 = 5.
- Hundreds: 9 - 8 = 1.
- Thousands: 4 - 1 = 3.
- Difference = 3,154.
D Your turn
E Ready to practise?
Key idea 1
Line up numbers neatly by place value columns before calculating.
Key idea 2
Always start computing from the Ones place and proceed left.
When adding
When adding, carry over when a column sum is 10 or greater.
When subtracting
When subtracting, regroup (borrow) when the minuend digit is smaller than the subtrahend digit.
Key idea 5
Check your subtraction by adding the answer back to the subtracted number.