Margin Formula

HELP???

I use a Sharp margin calculator quite often and would like to create a formula to do this in an Excel spreadsheet. Unfortunately I have a limited knowledge of MS Excel. Version is 202

Cost = $2.44
Sell= $2.99

I need to create a formula in order to calculate margin (% of Profit) which should is 18.39%

Can anyone help me with this?

Margin = 1 - Cost / Sell

Thanks shg and Martin!

I am almost there with what I need.

Attached is the spreadsheet that has an error with 1 or 2 formulas. Can anyone take a look at it to see what is wrong?

The difference between the results in the two formulas is that in the first case the unit cost is calculated as $2.4375, and in the second the cost is entered as $2.44 exactly.

The first result is the one that is technically correct, but with a difference of 0.08%, it isn't much different.

as shg says its coz you cant see the real result of h6/d6
cell is formated as "$"#,##0.00 giving only 2 decimal places
change to
"$"#,##0.000000
although result is shown as 2.44 excel calculates using the real value which is 2.4375