Sum Rules

Sum Rules

(1+2+3+………+n) = 1/n(n+1)
(12+22+32+………+n2) = 1/n (n+1) (2n+1)
(13+23+33+………+n3) = 1/4 n2 (n+1)2

Arithmetic Progression (A.P.)

a, a + d, a + 2d, a + 3d, ….are said to be in A.P. in which first term = a and common difference = d.
Let the nth term be tn and last term = l, then

a) nth term = a + ( n – 1 ) d
b) Sum of n terms = n/2 [2a + (n-1)d]
c) Sum of n terms = n/2 (a+l) where l is the last term

  • Tricks to Solve Number System
  • Unit Digit Multiplication
  • Examples of Number System with Explanation

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