Sumtime app for iPhone and iPad

You have a meeting at 18:30. You plan to go by train, and catch a cup of coffee before the meeting starts. When do you need to leave the office? Sumtime gives you the answer to this and similar questions!

Simple and Powerful:
• Sumtime is a universal time calculator.
• Add and subtract times to know "when" or "how long".
• Press and hold a time to switch between addition and subtraction.
• Enter as many rows as you like.
• Erase a row by simply swiping over it with your finger.
• Copy the result and paste it into other applications.
• The times you enter are kept on the sheet, even after a restart.