June 2018 Update

Task/Digital-root/Modula-2/digital-root.mod2

@@ -0,0 +1,51 @@
+MODULE DigitalRoot;
+FROM FormatString IMPORT FormatString;
+FROM Terminal IMPORT WriteString,WriteLn,ReadChar;
+
+TYPE Root =
+    RECORD
+        persistence,root : LONGINT;
+    END;
+
+PROCEDURE digitalRoot(inRoot,base : LONGINT) : Root;
+VAR root,persistence,num : LONGINT;
+BEGIN
+    root := ABS(inRoot);
+    persistence := 0;
+    WHILE root>=base DO
+        num := root;
+        root := 0;
+        WHILE num#0 DO
+            root := root + (num MOD base);
+            num := num DIV base;
+        END;
+        INC(persistence)
+    END;
+    RETURN Root{persistence, root}
+END digitalRoot;
+
+PROCEDURE Print(n,b : LONGINT);
+VAR
+    buf : ARRAY[0..63] OF CHAR;
+    r : Root;
+BEGIN
+    r := digitalRoot(n,b);
+    FormatString("%u (base %u): persistence=%u, digital root=%u\n", buf, n, b, r.persistence, r.root);
+    WriteString(buf)
+END Print;
+
+VAR
+    buf : ARRAY[0..63] OF CHAR;
+    b,n : LONGINT;
+    r : Root;
+BEGIN
+    Print(1,10);
+    Print(14,10);
+    Print(267,10);
+    Print(8128,10);
+    Print(39390,10);
+    Print(627615,10);
+    Print(588225,10);
+
+    ReadChar
+END DigitalRoot.