Mathmaticians do it an uncountable number of times. Mathmeticians do it with pencils. Mathematicians take it to the limit Mayor Daley does it 5 times every election day. Mechanical engineers do it automatically. Medical researchers make mice do it first.
Milkmen do it in the morning.
Milkmen deliver twice a week Millionaires pay to have it done. Miners sink deeper shafts. Miners do it with a bang. Ministers do it only on Sunday. Ministers do it vicariously.