Somebody gives you a penny one day. Then twice that the next day. Then twice that the next day. How much money do you have on the 25th day? How do I do this? I tried writed it down but I got to something like 25632 and that was only the fifteenth day!
2007-09-18 10:11:19 · 4 answers · asked by Ted (Guitar Legend) 3 in Science & Mathematics ➔ Mathematics
Yeah, but don't you have to add all of them up?
2007-09-18 10:36:33 · update #1
Keep multiplying by 2
1*2
2*2
4*2
8*2
16*2
32*2
64*2
128*2
256*2
512*2
1024*2
2048*2
4096*2
8192*2
16384*2
32768*2
65536*2
131072*2
262144*2
524288*2
1048576*2
2097152*2
4194304*2
8388608*2
16777216*2
33554432*2 day 25
At day 30 you have over a million dollars. $10737418.24
When running sequences like this i like to turn to my trusty MS Excel. With one simple formula, you can calculate it all. (=cell above * 2)
2007-09-18 10:35:02 · answer #1 · answered by saberhilt 4 · 0⤊ 1⤋
2^24
2007-09-18 10:20:50 · answer #2 · answered by Kenneth H 3 · 0⤊ 1⤋
1 +2^1+2^2 + 2^3 +..2^n + ..+2^24
This is a geometric series with r = 2
The sum is (1- 2^24)(1-2) = 2^24-1
2007-09-18 10:28:58 · answer #3 · answered by ironduke8159 7 · 0⤊ 1⤋
1 + 2 + 4 + ----
1 + 1(2)^1 + 1(2)^2 + 1(2)^3 + 1(2)^4 ------- 1(2)^(n-1)
nth term = 2^(n-1)
25 term = 2^(24) = 16777216 pennies
2007-09-18 10:20:53 · answer #4 · answered by mohanrao d 7 · 0⤊ 1⤋