Question

Find the sum of first 12 multiple of 7

Answer 1

a=7 d=7
a12=a+(n-1)d
a12=7+(12-1)7
=7+11*7
=7+77
a12=84
the sum of first 12 multiple of 7 is 84

Answer 2

First 12 multiple of 7    =  7, 14 ,21,28,35,42,49,56,63,70,77,84
Total Sum     =     546