# What is the CPLX button on a calculator?

On my cheap "dollar store" scientific calculator, it has a 2nd function button named "CPLX". When you press it, the calculator displays some text similar to the "DEG, RAD, GRAD" that says "CPLX". When in this mode, you can't add, subtract, multiply, or divide. The equals button doesn't even work.

What is this and how is it used? I'm wondering if maybe it's for complex numbers, seeing that there's also a "a" and a "b" button next to it.

-

## 1 Answer

This is for complex numbers, ones of the form $a+bi$ where $a,b$ are real and $i$ satisfies $i^2 = -1$.

Which calculator is it - you need the manual to learn to manipulate it.

-
+1 for the rtfm hint –  Hagen von Eitzen Oct 22 '13 at 18:07
More correctly $i$ is such that $i^2 = -1$ –  user88595 Oct 22 '13 at 18:08
@user88595 fixed. –  gt6989b Oct 22 '13 at 22:16
Thanks for your answer. It's a cheap dollar store calculator. Damin-locky KK-107A, to be exact. I can't find any manual for it online. –  Daniel Pendergast Dec 27 '13 at 23:28
@DantheMan here is a brief summary in Russian if it helps (1okey.ru/privat/instruction/instruction/…). They do agree that CPLX means a register of complex numbers... –  gt6989b Dec 30 '13 at 16:54