I don't remember what problem I struggled to understand... But it was something like this...
There are 3000 numbers so how many of them are odd.. Something like that.. Please give me a problem like that and please teach me!!!!
I hope you know what I am talking about!!
An example problem could be:
between 1 and 1000, how many numbers are neither divisible by 2 nor by 3.
So from 1 to 1000, 500 numbers are divisible by 2 (even numbers), and from 1 to 999, there are 333 numbers divisible by 3.
However, between 1 and 996 (next number is 1002)there are 166 numbers divisible by 6 (i.e. both 2 and 3).
So the number of numbers divisible by 2 OR by 3 would be 500+333-166=667, so there are 1000-667=333 numbers which are neither divisible by 2 nor by 3.