Answer :
The answer would be 3,200. you would take 40 ÷ 8 and get 5 doublings
so you double 100 to get 200 double 200 to get 400 and 400 to get 800 and 800 to get 1600 and 1600 to get 3200
so you double 100 to get 200 double 200 to get 400 and 400 to get 800 and 800 to get 1600 and 1600 to get 3200