Question

$3,6,18,72,$ ______, ______, then what is the value of the sum of two missing terms?

Answer 1

$3,6,18,72,\underset{–}{a},\underset{–}{b}$

The first number is multiplied by $2$ to obtain second, second by $3$ to obtain third, third by $4$ to obtain fourth and so on

$3\times 2=6;6\times 3=18;18\times 4=72;72\times 5=360=a,360\times 6=2160=b$

Hence the sequence shall be $3,6,18,72,360,2160$
So, answer is $(a+b)=2520$