How do birth contril pills prevent pregnancy

The birth control pill works by stopping sperm from joining with an egg (which is called fertilization). The hormones in the pill stop ovulation. No ovulation means there's no egg hanging around for sperm to fertilize, so pregnancy can't happen. The pill's hormones also thicken the mucus on the cervix.

Explanation:

well when looking at this if you think about it   negativley and positivley   react with each other and when the first layer gets full they add layers it starts with 2 on the first layer and it constantly goes on until the official number is there

9, 5, 10000000 ( that is supposed to be a ten for the last one)