Amazon.com : MATOLO Scientific Calculators for Students, 10-Digit LCD Screen, Solar & Battery Dual Power, 4 Function Calculator Small with Notepad for Office, Middle, High School & College, Mini Pocket Size :
Casio - FX-82MS. I bought it in high school, used it in University and now on my 4th year as a Professional Accountant. Haven't changed the battery once. : r/BuyItForLife