| --- |
| source: ncert |
| topic: numbers |
| class_level: class_7 |
| chapter: ch1 |
| difficulty: beginner |
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| |
| Class 7 | Ch1: Integers |
| Absolute value |a| = distance from zero (always positive). |
| Multiplication: same signs=positive, different signs=negative. |
| (+)×(+)=+, (-)×(-)=+, (+)×(-)=-, (-)×(+)=-. |
| Division: same sign rules as multiplication. |
| (-36)÷(-6)=+6. (-36)÷(+6)=-6. |
| Distributivity: (-7)×8+(-7)×2 = (-7)(8+2) = (-7)(10) = -70. |
| Properties: closure under +,-,×. Commutativity for + and ×. Associativity. a×0=0. |
| Temperature: -3°C fell 5°C = -3+(-5) = -8°C. |
| Common mistake: (-3)^2=+9 but -(3^2)=-9. Two negatives multiply to positive. |
