When the scales of field equipment for airborne forces were being considered - circa 1942 - one item was how many sheets of loo paper. This seemed to baffle the officers who formed the necessary (ney vital) sub committee, so history has it that they decided to ask the orderly who was looking after the staff.
He is reputed to have answered - quick as a flash - 'four, Sir'.
'On what do you base that' he was asked.
'One up, one down, one across and one for polish' was the response.
Old Duffer
PS The days when sheets of loo paper were over printed with Government property, loo paper was known as; the Army Blank Form.