I have a spreadsheet where column A has the number of miles and column B has
the total cost. I want to find the cost per mile.
In cell C1 I've put =B1/A1 and I've got the cost per mile.

Obviously I want to copy this down to get a result for B2/A2 etc but all I
get is the same answer as is in cell C1.

Why is this? Any ideas out there?