Well the game ins't so hard as it seems, took me around 2h (being half hours i was afk), so my tip is put the game in windowscreen and every time a new set of puzzles come out click on your desktop, the game will freeze but you will be able to see what numbers/letters/forms are there.

Other thing that helps is buying the power up (X), that will destroy highest number.

Hope this helps.

cheers