Practice gives you a fixed number of untimed questions with immediate answer feedback. Timed Round asks you to complete as many conversions as possible before the round clock expires. Speed Challenge gives every question its own time limit.
Difficulty changes the numbers being converted. Easy uses whole numbers from a smaller range. Medium introduces one decimal place and a wider range. Hard can use two decimal places and much larger distances.
Answer Precision controls how your answer is rounded. The app calculates from the exact relationship 1 mile = 1.609344 kilometers, then checks whether your numeric answer rounds to the required precision.
When Both Directions is selected, questions alternate unpredictably between kilometers-to-miles and miles-to-kilometers. Equivalent numeric formatting is accepted, so an answer such as 62.10 is treated the same as 62.1 when appropriate.
You can press Enter to submit, P to pause, or Esc to end the current round. Timers pause automatically when the page is hidden.