As a mathematics teacher, it always used to frustrate me that people seemed to increasingly rely on a calculator to do what could be accomplished in their head. Even if the answer requires more accuracy that can reasonably be accomplished mentally, the process of approximating a solution seems to be becoming a ‘lost art’.
The QAMA is a scientific calculator that won’t give you a true answer until you have offered a reasonable approximation of the solution you require. For example, if you need to know the square root of 2, the calculator will expect that you approximate the solution as being between 1.0 and 1.5 before it will give you the actual solution. Apparently the threshold for what qualifies as a ‘reasonable approximation’ varies from problem to problem.
The nice part is, the QAMA retails for around $20, very competitive with regular scientific calculators. Visit the QAMA site for more information.