ALGEBRA: 1. Sum of first n natural numbers = n(n+1)/2 2. Sum of the squares of first n natural numbers = n(n+1)(2n+1)/6 3. Sum of the cubes of first n natural numbers = [n(n+1)/2]^2 4. Sum of first n natural Read More …
Arithmetic Progression(AP) Arithmetic progression(AP) or arithmetic sequence is a sequence of numbers in which each term after the first is obtained by adding a constant, d to the preceding term. The constant d is called common difference. An arithmetic progression Read More …
Addition Rules for Even and Odd Numbers 1. Sum of any number of even numbers is always even 2. Sum of even number of odd numbers is always even 3. Sum of odd number of odd numbers is always odd Read More …
1. Multiplication of any two numbers, lies between 11 and 19 13*19 = (13+9)*10 + (3*9) = 220 + 27 = 247 Means add first number and last digit of the second number take zero in the third place of Read More …
