Why do even the simplest calculators feature a square root key?

[Gamo]

Today was thinking about the basic calculator on this thread about why it include the square root.

I found an article on how to calculate a "Display's Pixel Density"

Definition:
Pixel density is a metric telling us how many pixels there are in a fixed area of a display. It's a very important metric because it lets us know how closely packed the pixels on a display are. This is something that determines the quality, clarity, and readability of the image displayed. It is usually measured in a unit called pixels per inch (ppi).

Very often, when we are confronted with evaluating the quality of a display and/or comparing two or more displays together, we don't have all the information available. Something that is often missing is the pixel density, which is actually a very important metric and can provide us with valuable information about the picture quality we could expect. But we almost always know the size (diagonal) of the screen given in inches and the resolution. Having this information we could easily calculate the pixel density ourselves.

This is the formula: pixel density = √(Width^2 + Length^2) ÷ Screen Size

Remark: screen size is the diagonal of the screen.

Example using a basic calculator that included the square root
Using Citizen FS-50WHii model this one have [M+] feature.

A computer display is 21.5 inch with 1920x1080 resolution
Display size = 21.5 Inch
Width = 1920
Length = 1080

Enter steps to calculate:
1920 x = M+ display 3,686,400
1080 x = M+ display 1,166,400
MRC display 4,852,800
√ display 2202.9071
÷ 21.5 = 102.46079

Answer: Pixel Density = 102ppi (Close Approximation)

So here is one of the good use of square root on a basic calculator.

Gamo