Question

Find the smallest number which, when increased by one is exactly divisible by 12, 18, 24, 32 and 40

Answer 1

 L.C.M. of given numbers

2	12,	18,	24,	32,	40
2	6,	9,	12,	16,	20
2	3,	9,	6,	8,	10
3	3,	9,	3,	4,	5
	1,	3,	1,	4,	5

∴ L.C.M. = 2 x 2 x 2 x 3 x 3 x 4 x 5 = 1440 = One increasing 

∴ The required number = 1440 - 1 = 1439