 # 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: $$\begin{array}{l}\frac{a}{b}+\frac{c}{d}=\frac{ad+bc}{bd}\end{array}$$ Subtraction: $$\begin{array}{l}\frac{a}{b}-\frac{c}{d}=\frac{ad-bc}{bd}\end{array}$$ Multiplication:$$\begin{array}{l}\frac{a}{b}=\frac{c}{d} \text{ , then ad = bc}\end{array}$$ Division : $$\begin{array}{l}\frac{\frac{a}{b}}{\frac{c}{d}}=\frac{ad}{bc}\end{array}$$ Set properties: Commutative property: $$\begin{array}{l}A\cup B=B\cup A \\ A\cap B=B\cap A\end{array}$$ Associative property:$$\begin{array}{l}(A\cup B)\cup C=A\cup (B\cup C)\\ (A\cap B)\cap C=A\cap (B\cap C)\end{array}$$ Algebraic Expression Expansion: $$\begin{array}{l}(a+b)^{2}=a^{2}+2ab+b^{2}\end{array}$$ $$\begin{array}{l}(a-b)^{2}=a^{2}-2ab+b^{2}\end{array}$$ $$\begin{array}{l}a^{2}-b^{2}=(a+b)(a-b)\end{array}$$ $$\begin{array}{l}(x+a)(x+b)=x^{2}+x(a+b)+(ab)\end{array}$$ Consumer Math Formulas: Simple Interest: $$\begin{array}{l}S.I=\frac{PTR}{100}\end{array}$$ Where P=Principal, T= Time in years,R=Rate of interest per annum $$\begin{array}{l} Rate,R=\frac{100 \times S.I}{P \times T}\end{array}$$ $$\begin{array}{l}Principal,P=\frac{100 \times S.I}{R \times T}\end{array}$$ $$\begin{array}{l}Time,T=\frac{100 \times S.I}{R \times P}\end{array}$$ Discount = MP-SP Principal = Amount – Simple Interest $$\begin{array}{l}\text{If Rate of Discount is given, }Discount=\frac{Past\; Rate\; of\; Discount}{100}\end{array}$$ Time and Speed: $$\begin{array}{l}Speed=\frac{Distance\; travelled}{Time\; taken}\end{array}$$ $$\begin{array}{l}Number\; of\; Revolution=\frac{Distance\; travelled}{Circumference\; of\; the\; wheel}\end{array}$$ 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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