LCD of 1/2, 5/60, 5/12, 100/100

[Guest]

In trying to find the LCD of a string of numbers such as 1/2, 5/60, 5/12, 100/100 . One would first ignore the 100/100 because it is = to one. Then noting that 5/60 can be reduced to 1/12 would actually make this 1/2, 1/12, 5/12 and the LCD is 12. I am only asking if this is correct because I am locked in a debate with my teacher and classmates. I am being told NOT to reduce 5/60 which would make the LCD 300. But the order of math tells me to reduce before the calculations. Who is correct?

[Guest]

LCD of 2, 60, 12, 100 is 300 but
you have

1/2, 5/60, 5/12, 100/100 = 1/2, 1/12, 5/12, 12/12
so LCD is 12

Before calculating LCD you should reduce the fractions.

[Guest]

300 is also a common denominator but not the least common denominator.
By the way you are right not your classmates.