Many small edits.

man/man1/bc.1

@@ -267,7 +267,7 @@ define e(x) {
 for(i=1; i<=10; i++) print e(i)
 .EE
 .SH FILES
-.B /sys/lib/bclib
+.B \*9/lib/bclib
 mathematical library
 .SH SOURCE
 .B \*9/src/cmd/bc.y
@@ -281,12 +281,12 @@ No
 or
 .L !
 operators.
-.br
+.PP
 A
 .L for
 statement must have all three
 .LR E s.
-.br
+.PP
 A
 .L quit
 is interpreted when read, not when executed.