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 …
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 …