Three boys step off together from the same spot. Their steps measure 63 cm, 70 cm and 77 cm respectively. What is the minimum distance each should cover so that all can cover the same distance in complete steps?

Traffic lights at three different road crossing change after 48 seconds, 72 seconds and 108 seconds respectively. At what time will they change together again if they change simultaneously at 7 A.M.?

The HCF and LCM of two numbers are 9 and 270 respectively. If one of the numbers is 45, find the other number.

Find the HCF of 180 and 336. Hence, find their LCM.