Question

In a morning walk three persons step off together, their steps measure 80 cm, 85 cm and 90 cm respectively. What is the minimum distance each should walk so that they can cover the distance in complete steps?

Answer 1

Required minimum distance each should walk so, that they can cover the
distance in complete step is the L.C.M. of $80cm,85cm$ and $90cm$

$80=2\times 2\times 2\times 2\times 5$

$85=5\times 17$

$90=2\times 3\times 3\times 5$

$\therefore LCM=2\times 2\times 2\times 2\times 3\times 3\times 5\times 17$

$LCM=16\times 9\times 5\times 17$
$LCM=12240cm$