Hi I know the answe is probably easy but I seem to have brain block when it comes to this formula.

If 1000 mills of pertol cost $2.00 then the price goes up to $4.00 per 1000 mills of petrol what formula would you use to get the difference in mills in MS excel.

Ps I know the answe but not the formula to use as I want to enter the old price and the new price and get the difference in mills even if the difference is only as small 10cents or so.

Cheers Philippa

I haven't heard the term "mills" before - do you mean milliliters (or mL)?

If we let P1 = original price in dollars per 1000 mL, and P2 = new price in dollars per 1000 mL, then the change in price per mL is:


\frac {$P_2 -$ P_1} {1000mL}


For your example P1 = $2, P2 = $4, and change in price per mL is ($4-$2)/1000mL = $0.002/mL