YOC - Edutainment app

YOC ( Your Own Calculator ) practices mental arithmetics with school children as well as adults.
It will not only set tasks of the simple multiplication, but of all four basic arithmetic operations.Randomly the computer creates a task that has to be solved.
If the solution is correct the antennas of YOC blink green.
If the solution is incorrect the antennas glow red and YOC twists his eyes briefly.
Whenever a result has been typed, the solution can be accessed by pressing the solution button.
For the excercises formed by YOC, there are three ranges of numbers that can be chosen (all work with natural numbers): Calculating with numbers from 1-10, 1-20 and 1-100.
There is also the option for the user to enter numbers freely, in that case only integers can be entered.
Each of the operands of the arithmetic problem can be fixed by the user.
For example it is possible to determine the first number (e.g.
set to 5) and YOC will generate only the second operand (the range of the number to be created by YOC can be 1 to 10, 1 to 20 or 1 to 100).
YOC offers three options: The user may fixed the first operand only, the second operand only or both operands.
For subtraction problems where users choose and fix numbers themselves even negative result can be entered as solution.
Therefore the decimal point can be used as additional character.
The division problems pose a particular challenge, as the result may be a number containing a decimal point.For further improvement of YOC suggestions, comments and constructive criticism to via e-mail are welcome.