The LCM of these numbers is 198. (LCD is just the LCM of the denominators of fractions.)
The lcd of 11 is 11.
LCD(20, 6) = 60
lcd of 18 and 16 = 144
LCD(18, 21) = 126
LCD(5, 18) = 90
LCD(2, 9, 11) = 198.
18 is.
18
LCD(4, 8, 11) = 88.
the LCD is 6
lcd(9, 6) = 18.
You need at least two numbers to find something in common. If that's 191 and 811, the LCD is 154901. If that's 19, 18 and 11, the LCD is 3762.