64) What is the least count in a bevel protractor, if main scale graduations are 1 degree apart and number of graduations in Vernier scale is 12?

65) What is the approximate lateral surface area of a right circular cone with radius of base 5 cm and slant height 20 cm?

66) A fastener is designated as M5 x 0.8. If the length of the threaded portion is 4mm, the number of threads available is

67) Tool life in turning will decrease by maximum extent if we double the

68) What shall be the approximate mass of a 100mm diameter steel rod for one metre length?