Saving on a Scientific Calculator

When working on network-engineering projects, some calculations are in order in the realm of physics that may require a scientific calculator to reason about the changes of a signal for the information being transferred.

This dependency can be overcome, for quick and rough calculations, by using weaker estimations and a bit of mental gymnastics. The technique also helps you save on buying a scientific calculator for your engineering exams — if you're cheap, and enjoy the mental workout and the added challenge, like me.

First and most obvious: the ability to multiply, divide, add, and subtract in your head. Following that basic requirement, there's the need to memorize log₂(x) and log₁₀(x) and their inverses 2^0.x and 10^0.x for the primes under 20, plus the sine and cosine of 0, 15, 30, 45, 60, 75, and 90 degrees. After that, simply decompose bigger numbers to reach one you've memorized; if you land on a prime, e.g. log₁₀(131), just add or subtract 1 — we're using rough estimates anyway, so it shouldn't affect the output in a considerable way. If you're both lazy and cheap, memorizing the primes under 10 and the sin/cos of 30 and 45 should be enough for most calculations.

Happy studying