The Quick, Approximate, Mental Arithmetic (QAMA) calculator could end the math wars, writes Sanjoy Mahajan on Freakonomics.
I typed “25 x 37? and pressed “=”. A short underline cursor flashed away on the bottom left of the screen, without offering an answer. Instead, it demanded an estimate. Like a skilled tutor, it answered my question with its own.
When I entered 100, it asked again. For how could two numbers, each around 30, multiply only to 100? When I tried 400 and even 800, I still got no answer. Only when I tried 900 did the calculator answer my original question and tell me the exact answer (925). By experimenting, I found that, in order to get the exact answer, the estimate must be at least as close as 814–an error of 12 percent.
Useful? Good enough to enable The Treaty of QAMA?