Casio fx-3650P is a programmable scientific calculator manufactured by Casio Computer Co., Ltd. It can store twelve digits for the mantissa and two digits for the exponent together with the expression each time the "EXE" button is pressed. Pressing "Ans" also allows the calculator to use the previous result for further calculation as long as the calculator is not turned off after the previous calculation.

The calculator is available in six modes:

In this mode, if the result has both real and imaginary parts, an "R↔I" symbol will appear at the top right corner.

This mode is for statistical calculation. For some input data, the sum of squares of values (Σx²), sum of values (Σx), number of data (n), sample standard deviation (xσn-1) and population standard deviation (xσn) can be calculated.

This mode is for statistical calculation and can be divided further into:

For some input ordered pairs, one of the below can be calculated. (The availability differs from modes.)

Σx², Σx, n, Σy², Σy, Σxy, ${\displaystyle {\bar {x}}}$, xσn, xσn-1, ${\displaystyle {\bar {y}}}$, yσn, yσn-1, Regression coefficient A, Regression coefficient B, Correlation coefficient r, ${\displaystyle {\hat {x}}}$, ${\displaystyle {\hat {y}}}$, Σx³, Σx²y, Σx⁴, Regression coefficient C, ${\displaystyle {\hat {x}}}$₁and ${\displaystyle {\hat {x}}}$₂

The calculator can hold up to four programs with a total capacity of 360 bytes.