MathematicsClass 7Integers
Addition and Subtraction of Integers
Learning rules to add and subtract integers using number lines and algebraic principles.
Class 7 · MathematicsCBSE & ICSE SOF IMO
Definition
The addition and subtraction of integers involve moving left or right on the number line or applying specific sign rules. When adding integers with the same sign, we add their absolute values and keep the common sign. When subtracting an integer, we add its additive inverse (change the subtraction to addition and flip the sign of the second number).
Key formula
a - (-b) = a + b
Worked examples
1
Adding -5 and +3 results in -2 because the absolute value of the negative number is larger.
2
Subtracting -4 from +7 is calculated as 7 - (-4) = 7 + 4 = 11.
3
Adding -8 and -6 results in -14 by adding the absolute values and retaining the negative sign.
Common mistakes
- • Confusing the rules of multiplication signs with addition and subtraction rules (e.g., stating that negative plus negative equals positive).
- • Failing to change the sign of the subtrahend when performing subtraction.