To sort these from greatest to least, you see which number is closest to 1 (since they are all under 1). Look at the tenth place, and the largest digit in that place. This is an 8, so the largest is .836. Repeat again! The next one is a 6, so it goes .836, .683. After that, there are 2 numbers, .386 and .3, which are both in the .3, so the one with a higher hundreds place goes first. That is .386, so the final order is .836, .683, .386, .3.
Hope this helps!