A very simple solution, purely mathematical: you need to halve the level, and then halve the remnant (to a quarter) etc.
Not everything at the same moment, but by small bits and steps. You can look at the screenshots below as a reference:
Step 1
Step 2
Step 3
That's how you can complete each level fast. :-) Contrary to what one may think about such an easy solution, it does include a deal of risk for those who'd like some challenge.
