How many multiples of 3 are between 62 and 215?
The next multiple of 3 after 62 is 63..and 213 is the nearest multiple of 3 that is less than 215...the number of multiples is given by :
[(213 - 63) / 3 ] + 1 = [150/3] + 1 = 50 + 1 = 51