# Maths Formulas For Class 7

Mathematics is so important in our life. Because we use the mathematical equation in our daily life activities. Every student should have a clear understanding of the Maths formulas and their applications.

Refer the class 7 maths formulas to solve complex problems. Some topics involved in class 7 Mathematics are as follows:

- Number System
- Integers
- Fractions
- Decimals
- Mensuration
- Algebra
- Ratio and Proportion

## Class 7 Maths Formulas

Proportion Formula Rules: |

Addition: \(\frac{a}{b}+\frac{c}{d}=\frac{ad+bc}{bd}\) |

Subtraction: \(\frac{a}{b}-\frac{c}{d}=\frac{ad-bc}{bd}\) |

Multiplication:\(\frac{a}{b}=\frac{c}{d}\), then ad = bc |

Division : \(\frac{\frac{a}{b}}{\frac{c}{d}}=\frac{ad}{bc}\) |

Set properties: |

Commutative property: \(A\cup B=B\cup A \\ A\cap B=B\cap A\) |

Associative property:\((A\cup B)\cup C=A\cup (B\cup C)\\ (A\cap B)\cap C=A\cap (B\cap C)\) |

Algebraic Expression Expansion: |

\((a+b)^{2}=a^{2}+2ab+b^{2}\) |

\((a-b)^{2}=a^{2}-2ab+b^{2}\) |

\(a^{2}-b^{2}=(a+b)(a-b)\) |

\((x+a)(x+b)=x^{2}+x(a+b)+(ab)\) |

Consumer Math Formulas: |

Simple Interest, \(S.I=\frac{PTR}{100}\),
Where P=Principal, T= Time in years,R=Rate of interest per annum |

\( Rate,R=\frac{100 \times S.I}{P \times T}\) |

\(Principal,P=\frac{100 \times S.I}{R \times T}\) |

\(Time,T=\frac{100 \times S.I}{R \times P}\) |

Discount = MP-SP |

Principal = Amount – Simple Interest |

If Rate of Discount is given, \(Discount=\frac{Past\; Rate\; of\; Discount}{100}\) |

Time and Speed: |

\(Speed=\frac{Distance\; travelled}{Time\; taken}\) |

\(Number\; of\; Revolution=\frac{Distance\; travelled}{Circumference\; of\; the\; wheel}\) |

Area Formulas for 2D and 3D Figures: |

Area of Circle = π r^{2 }Sq units, where r is the radius
Area of Rectangle = l x b Sq.units, where l = length and b is breadth |

Total Surface Area for Cube = 6a^{2} sq.units
Total surface Area of cuboid = 2(lb+bh+hl) Sq.units |

Perimeter Formulas |

Square = 4s units, where s is side of square
Rectangle= 2(l+b) units, where l is length and b is breadth |

Volume Formulas: |

Volume of Cube = a^{3} cu.units
Volume of Sphere=4/3 π r Volume of Cylinder= π r |

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