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ElementaryArithmetic
Addition & Subtraction
Adding and taking away numbers
Master adding and subtracting numbers including carrying and borrowing.
✓ Addition: a + b = sum (order doesn't mat...✓ Subtraction: a − b = difference (order m...✓ Carry over when column sum > 9
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📖 Understanding Addition & Subtraction
Addition is combining two or more numbers to get a total. The symbol for addition is + and the result is called the sum.
Subtraction is finding the difference between two numbers — how much is left after taking away. The symbol is − and the result is called the difference.
When adding large numbers, we align the digits by place value (ones under ones, tens under tens) and add from right to left. If the sum exceeds 9, we carry over to the next column.
When subtracting, if a digit is smaller than the one being subtracted, we borrow 10 from the next column to the left.
🔑 Key Points to Remember
- ✓Addition: a + b = sum (order doesn't matter: 3+5 = 5+3)
- ✓Subtraction: a − b = difference (order matters: 8−3 ≠ 3−8)
- ✓Carry over when column sum > 9
- ✓Borrow when top digit < bottom digit in subtraction
- ✓Check subtraction by adding: if 10−3=7, then 7+3=10 ✓
#addition#subtraction#arithmetic#elementary#carry#borrow
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