There are 18 holes in a round of golf.
Normally 18 holes are played in a round of golf.
One round is 18 .. so 18 + 18= 36. ; 36 holes
It is a round of golf. It consists of playing 18 holes of golf.
There are 18 holes in golf. There are the front 9 and the back 9.
A full round of golf is 18 holes. Some courses are only 9 holes, in which case, the nine holes must be played twice. Any round which is less than 18 holes will not be considered a complete round.
There are usually 18 holes in a golf course; some have 9 holes or some multiplier of 9 holes. I have played at golf clubs with 9, 18, 27 and 36 holes. However, a standard "round of golf" at most golf clubs / courses involves 18 holes.
Holes 10-18 during an 18 hole round of golf.
9 or 18 holes?
A round of golf is played over 18 as in 1858 St Andrews - the home of golf - set a round at 18 holes for matches between it's members. This has been used every since.
When you say: "I have just completed a round of golf." Generally you are saying that you have just played golf. Usually 9 or 18 holes. I don't think it matters how many holes you play.