#### Answer

60

#### Work Step by Step

10,12,20
Find multiple of 10 = 10,20,30,40,50,60,70....
Find multiple of 12 = 12,24,36,48,60,72,84....
Find multiple of 20 = 20,40,60,80,100......
60 is the smallest number found in all the lists. So 60 is the least common multiple of 10,12 and 20