- When they give you two numbers, divide them.
The Great Green, one of my better IBM managers, used the ratios of key numbers to quickly evaluate proposals. Conversely, if a proposal didn’t have any key numbers, he knew the author was blowing smoke.
He attended a school budget meeting many years ago, wherein someone kvetched about the cost of and need for a semitrailer of paper every year. He estimated the number of sheets, divided by the number of students, then divided by the number of days in a school year. The answer came out to about one sheet of paper per student per day, which seemed like a perfectly reasonable number to him…
The Smell of Molten Projects in the Morning 