Casio fx-3650PII User's Guide

To perform a factory reset, press the 'MODE' button three times to access the 'CLR' menu. Choose 'All' by pressing the number '3' and confirm by pressing the '=' button.
Press the 'MODE' button until you reach the angle unit setting. Select '1' for degrees or '2' for radians.
Enter the 'MODE' menu and select 'SD' by pressing '2'. Input your data using the 'DATA' button and calculate the standard deviation using the 'SHIFT' and 'S-SUM' buttons.
Enter the 'EQN' mode by pressing 'MODE' and '5', then select '2' for quadratic equations. Input the coefficients and press '=' to view the solutions.
Yes, use the change of base formula: log_b(a) = log_c(a) / log_c(b), where 'c' is a base the calculator can handle, such as 10 or e.
The calculator does not show battery status. Replace batteries by removing the back cover and replacing the old batteries with new AAA batteries.
Press the 'a b/c' button to enter or convert numbers into fractions. Use the arrow keys to navigate between numerator and denominator.
Use the 'SHIFT' key followed by 'nPr' for permutations or 'nCr' for combinations after entering the required values.
To store a value, press 'SHIFT' followed by 'STO' and a letter (A, B, C, etc.). To recall, press 'RCL' and the letter.
Try resetting the calculator by pressing the 'RESET' button at the back using a pointed object. If it remains unresponsive, replace the batteries.