First, factor all these numbers:
- 18=2·3·3;
- 12=2·2·3;
- 14=2·7.
Then
- find all common factors for three numbers - this is factor 2 and write it as first factor of LCM(18,12,14);
- find all common factors for two numbers - this is factor 3 and write it as second factor of LCM(18,12,14);
- write all remaining factors.
At last, the least common multiple LCM(18,12,14)=2·3·3·2·7=252.
Answer: 252.