 # 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 r2 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 = 6a2 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 = a3 cu.units Volume of Sphere=4/3 π r3 cu.units, where r is the radius of the sphere. Volume of Cylinder= π r2h cu.units, where r is the radius of the base, h is the height of the cylinder.

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