Class 7 math formulas
Integers, linear equations, profit and loss, simple interest, triangles and the circle formulas used in Class 7 NCTB maths. Word problems need the formula and the steps.
Last updated: 2026-10-06
Class 7
Lower secondary
Class 7 adds integers, algebraic expressions, profit and loss, and simple interest. In word problems, substitute into the formula and show every step.
Integers and rational numbers
Subtracting a negative
a − (−b) = a + b
Sign rule for products
(+)(+) = +, (−)(−) = +, (+)(−) = −
Add rational numbers
a/b + c/d = (ad + bc) / (bd)
b ≠ 0 and d ≠ 0.
Algebraic expressions
Distributive law
a(b + c) = ab + ac
Value of an expression
substitute the given numbers for the letters, then simplify
Linear equations
ax + b = c
x = (c − b) / a
a ≠ 0. Do the same operation on both sides.
Equation with a fraction
(x / a) + b = c ⇒ x = a(c − b)
Ratio, percentage, profit and loss
Proportion
a/b = c/d ⇒ ad = bc
Profit
profit = selling price − cost price
Profit only if selling price is greater than cost price.
Loss
loss = cost price − selling price
Profit percentage
profit % = (profit / cost price) × 100
Loss percentage
loss % = (loss / cost price) × 100
Selling price from profit %
SP = CP × (100 + profit %) / 100
Selling price from loss %
SP = CP × (100 − loss %) / 100
Simple interest
Simple interest
I = (P × r × t) / 100
P is principal, r is the annual rate in percent, t is time in years. If time is in months, t = months/12.
Amount under simple interest
A = P + I = P(1 + rt/100)
Triangles and angles
Angle sum of a triangle
∠A + ∠B + ∠C = 180°
Isosceles triangle
equal sides ⇒ equal opposite angles
Equilateral triangle
each angle = 60°
Corresponding angles
parallel lines cut by a transversal ⇒ corresponding angles are equal
Alternate interior angles
parallel lines cut by a transversal ⇒ alternate interior angles are equal
Mensuration
Area of a triangle
A = (1/2) × b × h
Circumference of a circle
C = 2πr = πd
Textbooks often take π = 22/7 or 3.14.
Area of a circle
A = πr²
Area of a parallelogram
A = b × h
Data and mean
Mean
mean = (Σx) / n
How to use the Class 7 list
- In profit-loss, always start from cost price — Percentages are on CP unless the question clearly says otherwise.
- Convert months before simple interest — Time in the formula is in years, so 8 months is 8/12.
- Class 8 identities come next — Square and cube formulas are on the Class 8 page.
Official links
- NCTB — textbooks and syllabus — The national curriculum and textbook board publishes textbooks and syllabus notices.
Source: NCTB textbook structure and syllabus
FAQ
Is π 22/7 or 3.14?
Use whichever the question or your textbook states. If neither is given, 22/7 is the usual Class 7 choice when the radius is a multiple of 7.
Where is the Class 7 suggestion?
See the Class 7 suggestion for which chapters to practise first.