Complete Basic Arithmethic Forumula and Tricks for UPSC CSAT 2024 and 2025

On this page, we have compiled the complete list of short tricks and formula for CSAT questions related to Basic Arithmethic.

SUM OF NUMBERS

In the below formula, (n) = last natural number in the series given.

$$\text{sum of first (n) natural numbers} = \frac{n(n+1)}{2}$$

$$\text{sum of multiplication table of x} = \frac{x \times n(n+1)}{2}$$

$$\text{sum of square of first (n) natural numbers} = \frac{n\left(n+1\right)\left(2n+1\right)}{6}$$

$$\text{sum of the cube of first (n) even natural numbers} = {\left({n(n+1)} \over 2\right)}^2$$

$$\text{sum of the first (n) even natural numbers} = n(n+1)$$

$$\text{sum of the first (n) odd natural numbers} = {\left({n+1} \over 2\right)}^2$$

RULES OF DIVISION

• dividend = (divisor x quotient) + remainder
• divisor = (dividend - remainder) / quotient
• quotient = (dividend - remainder) / divisor
• remiander = dividend - (divisor x quotient)