Mental Calculation

2- the section called Calculation: it contains the addition; the subtraction; the multiplication and the mixture...according to my choice...I choose the desired operation and the birds begin to approach while trailing behind an operation; I have to look for the result; write it and click on the "Attak" button to kill the nearest bird....if the operation and just the bird will disappear if the operation is wrong the bird will approach and you will be a loser ....the operations must be solved quickly to win....purely educational application and allows the user to master mathematical operations while playing....great...!