proc Mode(Size, Array);         \Show the mode(s) of Array
int  Size, Array;
int  List, Count I, J, K, Max;
[List:= Reserve(Size*4);        \4 bytes per integer
Count:= Reserve(Size*4);
K:= 0;
for I:= 0 to Size-1 do
    [for J:= 0 to K-1 do
        if List(J) = Array(I) then  \item is in List
            [Count(J):= Count(J)+1; \ so increment its count
            J:= Size;
            ];
    if J = K then               \not already in List
        [List(K):= Array(I);
        Count(K):= 1;
        K:= K+1;
        ];
    ];
Max:= 0;                        \find maximum count
for J:= 0 to K-1 do
    if Count(J) > Max then
        Max:= Count(J);
for J:= 0 to K-1 do             \show Array item(s) with Max Count
    if Count(J) = Max then
        [IntOut(0, List(J));  ChOut(0, ^ )];
];

Mode(9, [1,2,3,4,5,5,5123,2,3])