Good Morning Alex: Please help. I'm trying to convert

8' x 10' x 21'

to Cubic Yards. I've compared my results against brouchers passed out by various manufactures, and their not even close. I thought the formula was: 8'x10'x21' = 1680.00 divided by 27 = 62.22. I have looked through your site and check many calculations, but could not find what I require. As you can see Math is not my fortay.

Thank you for your time
Ed