This music flashcard tool is designed to assist you in recognizing notes on the staff.
Ask yourself what the name of the note is, without any sort of calculation. If you don't instantly know what it is, work it out through whatever procedure you prefer. You can test yourself simply by rolling your mouse over the flashcard. Eventually, you want to get to the point where you instantly know the names of these notes without any conscious thought process of any kind.
Generate more music theory flashcards using the grey panel at the bottom of the screen. Select the notes to be tested from the popup menu in the panel. They are in a logical order of difficulty.