How the Reynold's number restricts the turbulant and streamline motion?

How many three-digit numbers are divisible by 7?

How would you show that the maximum number of electrons that can be accommodated in an orbit with principal quantum number 'n' is 2n^(2) ?

How many 5 digits telephone number can be formed from the digits from 0 to 9 when every number start with 23 (no digit being repeated in any number)

In a conference 10 speakers are present. If S_1 wants to speak before S_2a n dS_2 wants to speak after S_3, then find the number of ways all the 10 speakers can give their speeches with the above restriction if the remaining seven speakers have no objection to speak at any number.

How many even numbers are there between 91 and 259 ? Find also the sum of the even numbers between them.

how are frequency and wave number of electromagnetic radiation related to each other?