The French franc is obsolete and no longer legal tender and the
physical currency continues to be removed from circulation as
commercial banks come across it. You could buy francs privately, in
which case there is no "exchange" rate, just a bid/ask. As a practical
solution you would need to first convert pounds into euros and then
apply the fixed euro/franc exchange rate.
I am therefore addressing your question hypothetically. You have
provided an exchange rate between the British pound and French francs.
Was this the rate on some particular date? Are you saying that you have
pounds and wish to buy francs?
In any event, you could a couple of =ROUND() functions to solve your
problem.
Example:
Say you have 1,000 pounds, entered in A1. Your exchange rate is entered
in A2.
In A3, you'll need a formula that reads =ROUND(A1*A2,0)
This will round to the nearest whole franc, because you specified to
round to 0 decimal places. Using your rate, you will come up with 9,275
francs.
Taking things one small step further, you can now find the actual cost
in pounds of 9,275 francs (since 1,000 pounds does not equal exactly
9,275 francs).
In A4, enter =ROUND(A3/A2,2)
This converts your francs back into pounds and rounds out 2 decimal
places. You will find that 9,275 will cost you 999.96 pounds.
This is the simplest answer to your question and does not account for
any type of exchange or service fees, spreads between bid/ask rates,
denomination constraints when working with hard currency and coin, etc.