If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Your goal is to add the numbers shown on the screen in mind. Decide how the numbers will be shown on the screen by filling the blanks below. Depending on the blanks you filled the numbers will be shown on he screen and you will have to add these number. Wright the result you found and check if correct. Good Luck on this game!