Mathematics and Stastics

 Number system 1. Basic Formulae  (a + b)(a – b) = (a2 – b2) (a + b)2 = (a2 + b2 + 2ab) (a – b)2 = (a2 + b2 – 2ab) (a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca) (a3 + b3) = (a + b)(a2 – ab + b2) (a3 – b3) = (a – b)(a2 + ab + b2) (a3 + b3 + c3 – 3abc) = (a + b + c)(a2 + b2 + c2 – ab – bc – ac) When a + b + c = 0, then a3 + b3 + c3 = 3abc   2. Types of Numbers I. Natural Numbers Counting numbers 1,2,3,4,5,…1,2,3,4,5,… are called natural numbers   … Read more

   TIPS AND TRICKS FOR SPEEDY CALCULATIONS – MODULE III – MULTIPLICATION In this module we deal with techniques using which we can multiply two numbers in an unorthodox but quick manner. Firstly we take up some specific cases using which we come to generalized multiplication of any two given numbers. Multiplying two … Read more

 RELATIVE SPEEED AND TRAIN QUESTIONS Speed has no sense of direction unlike the velocity. Relative speed is the speed of one object as observed from another moving object. Questions on train are the classic examples of relative speed and in all these questions it is assumed that trains move parallel … Read more

   TIPS AND TRICKS FOR SPEEDY CALCULATIONS – MODULE I – SQUARES In this module we deal with finding squares of two digit and three digit numbers and some special cases arising out of these forms. This section is not only important in itself but forms the very basis of more tedious and … Read more

          Important Formulas – Percentage Percentage Percent means for every 100 So, when percent is calculated for any value, it means that we calculate the value for every 100 of the reference value. percent is denoted by the symbol %. For example, x percent is denoted by x% x%=x/100 Example : … Read more