168.
840
LCD(8, 21, 7) = 168.
LCD(9, 21) = 63
LCD(18, 21) = 126
LCD(6, 8) = 24
LCD(8, 3) = 24.
LCD(12, 8) = 24.
LCD(715, 8) = 5720
LCD(8, 100) = 200
I think what you might have meant was LCD (Lowest Common Denominator) The LCD for 11/7 and 3/8 is 56 Making equivalent fractions using the LCD: 11/7 becomes 88/56 3/8 becomes 21/56
LCD(21, 13, 14, 15) = 2730
The LCD of the given three numbers is 8