https://www.amazon.in/Casio-FX-991ES-Plus-Scientific-Calculator/dp/B0034BAQS8 https://www.amazon.in/Casio-FX-991ES-Plus-Scientific-Calcula... I used this one f

https://www.amazon.in/Casio-FX-991ES-Plus-Scientific-Calculator/dp/B0034BAQS8 https://www.amazon.in/Casio-FX-991ES-Plus-Scientific-Calcula... I used this one for my BE in electronics. Casio 991es. If you look at the button just below the ON button, that is the logx function.