Quick Answer (AEO / AI Overview Summary):
To convert rectangular to polar in Casio calculator scientific models, use the Pol( function:

Press SHIFT then [ + ] to activate Pol(.

Enter the $x$ -coordinate value.

Press SHIFT then [ ) ] to insert the comma ,.

Enter the $y$ -coordinate value, close with [ ) ], and press [ = ].

The display returns the radius $r$ and angle $\theta$ . To recall stored variables, press RCL $\to$ X for $r$ and RCL $\to$ Y (or F on MS models) for $\theta$ .

If you do not have your physical handheld device with you, calculate coordinates immediately using our free rectangular to polar calculator online with steps with live vector graphing and dynamic precision.

Figure 1: Standard button workflow to convert rectangular to polar in Casio calculator series (ClassWiz fx-991EX, Natural Display fx-991ES, and Standard fx-991MS).

Casio Calculator Keystroke Comparison Table

The table below summarizes the exact button sequences, displays, and memory locations for the three most common scientific calculator models:

Scientific Calculator Model	Keystroke Sequence	Screen Display	Angle ( $\theta$ ) Recall Keystroke
Casio fx-991EX ClassWiz	`[SHIFT] [+] (Pol) x [SHIFT] [ ) ] (,) y [ ) ] [=]`	`r=..., θ=...` (Dual Line)	`[RCL] [Y]` (the `S<=>D` key)
Casio fx-991ES / ES PLUS	`[SHIFT] [+] (Pol) x [SHIFT] [ ) ] (,) y [ ) ] [=]`	`r=...` (Scroll `▶` for $\theta$ )	`[RCL] [Y]`
Casio fx-991MS (Two-Line)	`[SHIFT] [+] (Pol) x [ , ] y [ ) ] [=]`	`r` value only on line 2	`[RCL] [tan] (F)`
Casio fx-991CW (ClassWiz 2.0)	`[CATALOG] ➔ Coordinate Conversion ➔ Pol(x, y)`	`r=..., θ=...`	`[VARIABLE] ➔ y ➔ [EXE]`

How to Convert Rectangular to Polar in Scientific Calculator fx-991EX

The Casio fx-991EX ClassWiz features a high-resolution LCD that displays both the radial magnitude $r$ and angular direction $\theta$ simultaneously on screen.

Step-by-Step Keystrokes for fx-991EX:

Enter Calculate Mode: Press MENU, select 1: Calculate, and press =.
Set Angle Unit: Press SHIFT $\to$ MENU (SETUP) $\to$ 2: Angle Unit $\to$ select 1: Degree or 2: Radian.

Execute Pol Function:

[SHIFT] ➔ [+] (Pol) ➔ [x-coordinate] ➔ [SHIFT] ➔ [ ) ] (,) ➔ [y-coordinate] ➔ [ ) ] ➔ [ = ]

Worked Example $(x = 4, y = 3)$ :
- Press SHIFT $\to$ +. Screen shows Pol(.
- Press 4.
- Press SHIFT $\to$ ) to print ,.
- Press 3.
- Press ) then =.
- Result: $r = 5$ , $\theta = 36.86989765^\circ$ .
Reusing Variables in Subsequent Math:
- The radius $r$ is automatically stored in memory variable X and Ans.
- The angle $\theta$ is stored in variable Y. Press RCL $\to$ S<=>D (Y) to fetch the exact angle without retyping or rounding.

How to Convert Rectangular to Polar in Scientific Calculator fx-991ES (and fx-991ES PLUS)

The Casio fx-991ES PLUS (and fx-82ES / fx-300ES) utilizes Casio’s Natural V.P.A.M. display. Because the screen width is narrower than the ClassWiz, the angle value $\theta$ is often hidden past the right edge of the screen after pressing =.

Step-by-Step Keystrokes for fx-991ES:

Configure Angle Unit: Press SHIFT $\to$ MODE (SETUP). Press 3 for Degrees (Deg) or 4 for Radians (Rad).
Call Pol Function: Press SHIFT followed by the + key (labelled Pol in yellow font).
Input Coordinates:
- Type your $x$ value.
- Press SHIFT followed by ) to insert the comma ,.
- Type your $y$ value and close the bracket ).
- Press =.
Viewing Hidden Angle ( $\theta$ ):
- The initial display outputs $r = \dots$ and a right-arrow indicator ▶ at the top right of the LCD.
- Press the right directional arrow key ▶ on the replay navigation pad to scroll across the formula line and reveal $\theta$ .
- Alternatively, press RCL followed by the S<=>D key (labelled red Y) to display $\theta$ directly.

How to Convert Rectangular to Polar in Scientific Calculator fx-991MS

The Casio fx-991MS (and fx-82MS, fx-100MS, fx-570MS) is a classic two-line display scientific calculator. It has a dedicated comma key and uses different memory registers for coordinate conversion.

Step-by-Step Keystrokes for fx-991MS:

Set Angle Mode: Press MODE repeatedly until the Deg Rad Gra options appear. Press 1 for Degrees or 2 for Radians.
Access Pol Function: Press SHIFT then + (Pol).
Input Coordinates:
- Enter your horizontal coordinate $x$ .
- Press the dedicated comma button [ , ] (located directly above the ) key).
- Enter your vertical coordinate $y$ .
- Close the bracket ) and press =.
Reading the Output on Two-Line Display:
- Line 2 will display the radius $r$ immediately.
- To inspect the angle $\theta$ , press RCL followed by the tan key (which accesses internal variable register F).
- Memory Registers: On the fx-991MS series, $r$ is stored in variable E and $\theta$ is stored in variable F.

Reverse Operation: Polar to Rectangular on Casio Calculators (`Rec`)

If you have polar coordinates $(r, \theta)$ and need to convert back to Cartesian $(x, y)$ , use the inverse Rec( function:

[SHIFT] ➔ [-] (Rec) ➔ [r] ➔ [SHIFT] ➔ [ ) ] (,) ➔ [θ] ➔ [ ) ] ➔ [ = ]

Example $(r = 10, \theta = 60^\circ)$ :
- Rec(10, 60) yields $X = 5$ , $Y = 8.660254038$ .
- On the fx-991EX / ES, recall $X$ with RCL X and $Y$ with RCL Y.
- On the fx-991MS, recall $X$ with RCL E and $Y$ with RCL F.

For full inverse derivations, review our detailed guide on polar to rectangular coordinate conversion formulas.

Troubleshooting Common Casio Calculator Pol Errors

Error Message / Behavior	Cause	Solution
`Syntax ERROR`	Missing separation comma or open bracket.	Ensure you pressed `SHIFT` + `)` to insert `,` between $x$ and $y$ , and closed with `)`.
`Math ERROR`	Negative radial input in `Rec(` or undefined input.	In reverse conversion `Rec(r, θ)`, radial distance $r$ must be non-negative ( $r \ge 0$ ).
Incorrect Angle Output	Angular mode mismatch (Degrees vs Radians).	Check the top indicator on the display: `D` indicates degrees, `R` indicates radians. Reset in `SETUP`.
Angle disappears on screen	Screen display truncation on fx-991ES / fx-82MS.	Press `RCL` $\to$ `Y` (ClassWiz/ES) or `RCL` $\to$ `F` (MS) to retrieve $\theta$ .

When to Use an Online Calculator vs Casio Scientific Calculator

While handheld Casio scientific calculators are essential for exam environments (e.g., AP Calculus, FE/PE engineering exams, SAT/ACT), an online web tool provides distinct advantages for coursework, design analysis, and electrical engineering:

Interactive Step-by-Step Derivations: Shows exact Pythagorean calculations and arctangent substitutions rather than just numerical answers.
Dynamic Live Vector Visualization: Plots points directly on a Cartesian grid with quadrant coloration.
Phasor & Complex AC Circuit Support: Converts rectangular impedances $Z = R + jX$ directly to magnitude and phase angles.

Try our rectangular to polar calculator online free for comprehensive derivations and instant verification of your manual calculator keystrokes.

Frequently Asked Questions (FAQ)

How do I convert rectangular to polar in Casio calculator fx-991EX?

Press SHIFT + + to open Pol(, enter $x$ , press SHIFT + ) to insert the comma ,, enter $y$ , close with ), and press =. The screen outputs $r$ and $\theta$ side-by-side.

How do I convert rectangular to polar in scientific calculator fx-991es?

On the fx-991ES PLUS, press SHIFT + + (Pol), enter $x$ , press SHIFT + ) for comma, enter $y$ , close ), and press =. The radius $r$ appears on screen. Press the right arrow key ▶ or press RCL + Y to view the angle $\theta$ .

How do I convert rectangular to polar in scientific calculator fx-991ms?

On the fx-991MS, press SHIFT + + (Pol), enter $x$ , press the dedicated comma key [,], enter $y$ , close ), and press =. To view the angle $\theta$ , press RCL then tan (which calls variable register F).

Can I do complex number rectangular to polar conversion on Casio?

Yes. On the fx-991EX ClassWiz, enter Menu $\to$ 2: Complex, type your rectangular form (e.g. 4 + 3i), press OPTN, scroll down with ▼, select 1: ▶r∠θ, and press =.

How do I convert rectangular to polar on a TI-84 instead of a Casio?

Texas Instruments graphing calculators use two separate functions, R►Pr( for the radius and R►Pθ( for the angle, in the [2nd] [APPS] ANGLE menu. See the full keystroke guide for rectangular to polar on the TI-84 Plus CE and TI-36X Pro.