Sum Rules
(1+2+3+………+n) = 1/2 n(n+1)
(12+22+32+………+n2) = 1/6 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