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Stock Math Formula


Don't know if I should post it on challenge, excel question, or this but I guess I'll post it here.
I am getting confused in how to properly present it despite the answer is clear. For example
If 2 stock(A) are worth$10(B) and it goes down to $2(C) that is a 80% loss(D)

But if it goes up and you buy it at $3(E) and you expect it to go to $4(F) which is a 25%(G) potential gain,
So what would the excel formula be in how shares to buy the stock(H) at $3 (H) a share if it will go to $4(F) to get you original $10 (B) back ?
Obviously this needs would benefit from multiple cells to be able to adjust accordingly and see all the values to be adjusted for other circumstances.
Also it can't be a fraction since you cant buy a fraction of a stock usually.


Excel Ninja
So, from $10 to $2, you lost $8.

To gain back $8 lost, with expected value appreciation of $1 on each stock... You need to buy 8 stocks.

Or do you mean that you need to buy 3 shares at $3, each appreciating by $1, and net value at end being $12?

I'm assuming that this is not options trading (put/call) and just straight stock trade.

Note: This doesn't account for transaction fees, minimum trade volume and other factors that will impact stock trade.


I figure this would confuse many.

If it goes up 25% 3 shares at $3 at a total of $9 as you state can not reach 10. which would get 2.25 to be a total of 5.25

What I get for an answer is 20 shares
since you would need 20 shares at $3 which would be $30 which 25% gain would be 7.5% and with the 3 you have that would be 10.5
Am I wrong?

not option and not accounting for others since that would over complicate. but what would that be I dont know.
Again all in the excel formula
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Excel Ninja
Math is simple enough, you just have to show us how your workbook is set up.

But, why $10? You stated you lost 80% of initial $10 value. Which equates to $8.00 loss.

So the difference that you need to make up is $8 and not 10.

But since you mentioned 2 @ $10, loss is $16.

25% gain on $3 stock is $0.75.

So 16/0.75 = 21.33333, or 22 shares are needed.

So... =ROUNDUP(10*(1-0.8)*2/(3*0.25),0)

If this isn't correct, you'll need to give more detailed explanation.