libc: Improve {,l,ll,imax}div(3) manpages

Mainly rename numerator parameter of div(3) and ldiv(3) from num to
numer, and explicitly specify what "numer", "denom", and "rem" mean in
the manpages.

MFC after:	3 days
Obtained from:	https://github.com/apple-oss-distributions/libc (partially)
Sponsored by:	Klara, Inc.

lib/libc/stdlib/div.3

@@ -27,7 +27,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd November 14, 2001
+.Dd February 12, 2026
 .Dt DIV 3
 .Os
 .Sh NAME
@@ -38,21 +38,23 @@
 .Sh SYNOPSIS
 .In stdlib.h
 .Ft div_t
-.Fn div "int num" "int denom"
+.Fn div "int numer" "int denom"
 .Sh DESCRIPTION
 The
 .Fn div
 function
 computes the value
-.Fa num/denom
-and returns the quotient and remainder in a structure named
+.Fa numer Ns / Ns Fa denom
+(numerator/denominator).
+It returns a structure named
 .Fa div_t
 that contains two
 .Vt int
 members named
 .Va quot
-and
-.Va rem .
+(quotient) and
+.Va rem
+(remainder).
 .Sh SEE ALSO
 .Xr imaxdiv 3 ,
 .Xr ldiv 3 ,

lib/libc/stdlib/div.c

@@ -35,12 +35,12 @@
 #include <stdlib.h>		/* div_t */
 
 div_t
-div(int num, int denom)
+div(int numer, int denom)
 {
 	div_t r;
 
-	r.quot = num / denom;
-	r.rem = num % denom;
+	r.quot = numer / denom;
+	r.rem = numer % denom;
 
 	return (r);
 }

lib/libc/stdlib/imaxdiv.3

@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd November 14, 2001
+.Dd February 12, 2026
 .Dt IMAXDIV 3
 .Os
 .Sh NAME
@@ -39,9 +39,9 @@ The
 .Fn imaxdiv
 function computes the value of
 .Fa numer
-divided by
+(numerator) divided by
 .Fa denom
-and returns the stored result in the form of the
+(denominator) and returns the stored result in the form of the
 .Vt imaxdiv_t
 type.
 .Pp

lib/libc/stdlib/ldiv.3

@@ -29,7 +29,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd April 3, 2022
+.Dd February 12, 2026
 .Dt LDIV 3
 .Os
 .Sh NAME
@@ -40,21 +40,23 @@
 .Sh SYNOPSIS
 .In stdlib.h
 .Ft ldiv_t
-.Fn ldiv "long num" "long denom"
+.Fn ldiv "long numer" "long denom"
 .Sh DESCRIPTION
 The
 .Fn ldiv
 function
 computes the value
-.Fa num Ns / Ns Fa denom
-and returns the quotient and remainder in a structure named
+.Fa numer Ns / Ns Fa denom
+(numerator/denominator).
+It returns the quotient and remainder in a structure named
 .Vt ldiv_t
 that contains two
 .Vt long
 members named
 .Va quot
-and
-.Va rem .
+(quotient) and
+.Va rem
+(remainder).
 .Sh SEE ALSO
 .Xr div 3 ,
 .Xr imaxdiv 3 ,

lib/libc/stdlib/ldiv.c

@@ -35,12 +35,12 @@
 #include <stdlib.h>		/* ldiv_t */
 
 ldiv_t
-ldiv(long num, long denom)
+ldiv(long numer, long denom)
 {
 	ldiv_t r;
 
-	r.quot = num / denom;
-	r.rem = num % denom;
+	r.quot = numer / denom;
+	r.rem = numer % denom;
 
 	return (r);
 }

lib/libc/stdlib/lldiv.3

@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd November 14, 2001
+.Dd February 12, 2026
 .Dt LLDIV 3
 .Os
 .Sh NAME
@@ -39,9 +39,9 @@ The
 .Fn lldiv
 function computes the value of
 .Fa numer
-divided by
+(numerator) divided by
 .Fa denom
-and returns the stored result in the form of the
+(denominator) and returns the stored result in the form of the
 .Vt lldiv_t
 type.
 .Pp