One night you put a quarter into a slot machine and get back two quarters. The next night, you put these two quarters back in the machine one at a time, and each time two quarters came out. This pattern continued through the sixth night, after which you took your winnings and went home. How many quarters were fed into the machine?
A)64
B)63
C)47
D)31

Question

Quizplus · Accepted Answer

On the second night, you put in 2 quarters and got back 4. 
On the third night, you put in 4 quarters and got back 8. 
On the fourth night, you put in 8 quarters and got back 16. 
On the fifth night, you put in 16 quarters and got back 32. 
On the sixth night, you put in 32 quarters and got back 64.

So the total number of quarters fed into the machine is: 
1 + 2 + 4 + 8 + 16 + 32 = 63.

Therefore, the correct answer is B) 63.

One Night You Put a Quarter into a Slot Machine