bro you can go for either citizen ct - 512 it has 12 digit number input support price 180 rs
or you can go
casio mj 120d it also has 12 digit number input support with 150steps error check and you can also calculate tax price 418 rs both available on amazon. i have both this calculator for last 4 year
Only for Calculating Marks for student ?
Then go for Any stationary shop , and buy a basic calculator made by Any brand like casio , cello , orpat.
Price will vary from 200-300.
bro use this button to utilize memory calculating just see the portion i ost on pic
for casio memory calculating button bellow division button
and for citizen bellow on button