Why is the sticky bit mentioned twice in chmod but only once in the ls output?

My task was to configure a directory so that users in a group could only delete files they own. I used

1771 RandD

, as suggested by lab instructions, to accomplish this. When running

-l

, the permissions were displayed as

--t

. I understand why there is a

at the end of the permissions, since the last 1 in

1771 RandD

is responsible for other permissions. However, what is the point of the first 1 if

is not displayed in the user's permissions section?