Problem Type Selection:
\Select the level you wish to practice. Totally 3 levels are available.
\Play: Starts presenting the problems. By changing any of the configurable values the Play button could be pressed again.
\Lock Selection: pressing this button will lock all the user selections. Lock image will appear in the status box. Also Lock Selection button will be changed to Unlock button and also reset the status fields. Pressing Unlock will release the lock.
\Enter the answer: Perform the requested time arithmetic and enter the answer. If the Answer is correct then next problem will be displayed. If it is wrong then help will be provided to read the time.
Show Answer Will display the corresponding time.