Calculator Apps
Big buttons, easy math.
1. Built-in works fine
iPhone and Android both have calculator apps. Free, big buttons in landscape mode.
2. Tip Calculator
Built into iPhone Calculator. Or any of dozens of free tip apps.
3. Currency converter
XE Currency. Free. Live rates for travel.
4. Mortgage calculator
Bankrate's free app. Estimate monthly payments and total interest.
5. Unit converter
Inches to centimeters, gallons to liters. Useful when traveling abroad.
6. Voice calculator
Hey Siri or Hey Google, what's 25% of $84? Instant answer.
Use phone in landscape (sideways) mode. Calculator shows scientific functions too.