240 students are participating a big performance show. They stand in a row and face to their coach. The coach askes them to count numbers from left to right, starting from 1. (Of course their counts be like 1,2,3,...)The coach askes them to remember their number and do the following action:
First, if your number is divisible by 3 then turn around.
Then, if your number is divisible by 5 then turn around.
Finally, if your number is divisible by 7 then turn around.
(a) How many students are face to coach now?
(b) What is the number of the 66th student counting from left who is face to coach? combinatoricsnumber theory