per S3 W1
during each hour etc:
The park attracts 4 million visitors per year.
miles/kilometres per hour (=used for measuring speed)
a speed limit of 40 miles per hour
How much does it cost per kilo?
rooms costing £40 per night
Admission is £9.95 per adult.
My car does 12 miles per litre (=for each litre of petrol).
The meal cost $25 per head (=for or by each person).
according to something:
The work was carried out as per your instructions.
used when something annoying happens which has often happened before:
Jenny was late, as per usual.