Bin/Oct/Dec/Hex converter.
Celsius, Fahrenheit, Kelvin.
Convert Unix time and dates.
Pixels per inch from size and pixels.
Resize & simplify ratios.
Future value with compounding.
Monthly payment for a loan.
Increase/decrease from A to B.
Tip + split the bill.
Body Mass Index from height and weight.
Days between two dates.
Calculate age from birthdate.