After 1 month, the book club had 5 members. The number of club members doubled every month.

How many members did the club have after 4 months?

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Alright, take it step by step ... in month one, they had 5 members.

if the number doubles each month, then the second month they will have a total of ten members, right? in the third they will have twice the number before, or 2 times 10, 20. if you double 20, you have the number of people in the fourth month, giving you a grand total of 40.

Since you know that the number of club members doubled every month, you would multiply how much members in one month by 2

1 month = 5 members multiply by 2

2 month = 10 members multiply by 2

3 month = 20 members multiply by 2

4 month = 40 members

So, for each moth you multiply it by 2.

After 4 months there will be 40 members