Question

In a colony of 100 blocks of flats numbering 1 to 100, a school van stops at every sixth block while a school bus stops at every tenth block. On which stops will both of them stop if they start from the entrance of the colony?

Answer 1

There are 100 blocks in a colony numbering 1 to 100.

A school van stops at every sixth block and a school bus stops at every tenth block.

We have to find the common stops at which they both stop if they start from a same entrance.

∴ We need to find the LCM of 6 and 10

2	6, 10
3	3, 5
5	1, 5
	1, 1

∴ The LCM of 6 and 10 is 2 × 3 × 5 = 30. 

i.e., Firstly both will stop at 30^th block, then at 60^th block and lastly at 90^th block.