MathDB

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

66^{\text{th}}

student counting from left who is face to coach?

Problem Statement