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[Solved] Exponential growth
Posted: Fri Jan 19, 2018 5:54 pm
by elvis35to05
Hi room,
anyone have idea how do do the formula to find out:-
how to do the penny double the amount every day project. like
day 1==1 penny
day 2==2 penny
day 3== 4 penny
day 4== 8penny
day 5== 16penny
thanks in advance.
Re: exponential growth
Posted: Fri Jan 19, 2018 6:34 pm
by RoryOF
In cell A1 enter 1; in cell A2 enter "=A1*2" (no quotes). Select cell A2 by clicking on it, and pull down using the little black dot on bottom right corner of the selected cell.
Re: expotential growth
Posted: Fri Jan 19, 2018 6:49 pm
by keme
And if you want to enter the number of days passed, and just calculate for that day, you just ...
... oops, just a thought: Are we doing schoolwork for you?
Just in case, for starters I only give you something to tease your memory: There is a math operation that says "multiply number by itself n times". You need to find the number to multiply by itself, and the operation in question.
If you promise that you really need the answer for some other work and it is not something you are supposed to learn, you will get the solution spelled out. We'll trust your word.
Re: exponential growth
Posted: Fri Jan 19, 2018 7:41 pm
by Zizi64
penny = 2^(day-1)
Re: Exponential growth
Posted: Sat Jan 20, 2018 12:17 am
by elvis35to05
Thanks for your help,RoryOF, keme, and Zizi64, much appreciated.
keme, No its not school work lol, i,m 70yrs old next month, i was just curious about the question of if you would take a million pounds or a penny doubled for one month.
Re: Exponential growth
Posted: Sat Jan 20, 2018 10:40 am
by keme
elvis35to05 wrote:Thanks for your help,RoryOF, keme, and Zizi64, much appreciated.
keme, No its not school work lol, i,m 70yrs old next month, i was just curious about the question of if you would take a million pounds or a penny doubled for one month.
Your first post, asking a typical math assignment from class, so I had to ask. Sorry that the revelation was delayed. I hope you didn't lose millions because of that.
Re: Exponential growth
Posted: Sat Jan 20, 2018 11:19 am
by RoryOF
elvis35to05 wrote:Thanks for your help,RoryOF, keme, and Zizi64, much appreciated.
keme, No its not school work lol, i,m 70yrs old next month, i was just curious about the question of if you would take a million pounds or a penny doubled for one month.
If you find out how to do this, please let us know!
Re: Exponential growth
Posted: Sat Jan 20, 2018 2:57 pm
by elvis35to05
Hi room
i used formula from RoryOF,
it was just a curiosity of mine, i hope i did it right.
thanks for your help.
the question was you get a penny a day doubling every day for 31 days i get
3,221,225,471. pennies
32,212,254.71 pounds
Re: Exponential growth
Posted: Sat Jan 20, 2018 4:08 pm
by Lupp
Even if I double the first penny already on day 1 of january, I only get 21 474 836.48 £ at the end of 31 january. I'm feeling so poor. What did I wrong?
Re: Exponential growth
Posted: Sat Jan 20, 2018 4:23 pm
by elvis35to05
hi Lupp,
so far except for a penny you got same as me,
this is the total for 30 days but you add the amount from day 31 to what you have.
Re: Exponential growth
Posted: Sat Jan 20, 2018 4:28 pm
by jrkrideau
@ Lupp
Same here. Perhaps short term exchange rate problems?
Re: Exponential growth
Posted: Sat Jan 20, 2018 4:33 pm
by RoryOF
How will we spend all this money?
Re: Exponential growth
Posted: Sat Jan 20, 2018 4:36 pm
by elvis35to05
hi RoryOF ,
if only ha ha, we would have a great life.
thanks
Re: Exponential growth
Posted: Sat Jan 20, 2018 6:41 pm
by Lupp
How will we spend all this money?
I would surely advertise in TV. What about "Rory for PM!"?
Re: Exponential growth
Posted: Sun Jan 21, 2018 9:32 am
by keme
elvis35to05 wrote:Hi room
i used formula from RoryOF,
...
the question was you get a penny a day doubling every day for 31 days i get
...
If you add the amounts up, it is a slightly different formula. Just remove the parenthesis.
That will take care of the one-day offset and one penny difference.
Re: Exponential growth
Posted: Sun Jan 21, 2018 10:00 am
by Zizi64
elvis35to05 wrote:
Hi room
i used formula from RoryOF,
...
the question was you get a penny a day doubling every day for 31 days i get
...
If you add the amounts up, it is a slightly different formula. Just remove the parenthesis.
Code: Select all Expand view
penny = 2^day-1
That will take care of the one-day offset and one penny difference.
In my opinion the difference _is_ inside the perentheses:
penny = day^(day-1) ... if you started (with 1 penny) on the first day (day 1).
penny = day^(day) ... if you started on the 0th day.
The difference is not negligible
Please send me the amount of the positive difference...