Casio fx - 991ES plus is the scientific caluculator which is used by enginers and all degree programmers
It gives esay way to caluculate the numaricals it costs up to 700-900rupees
Many of the geniouses students are using this . it is having 3 years warrenty
Easy to caluculate logrithems , algebra, trignometry problems
It is works by solar or battrey cells
Another product also avilable in markert that is belongs to cello company which rates. 300 rs but it not working well and it works by battery cells it is negeitive and no warrenty to cello product