Nice primes: Difference between revisions

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     % returns the digital root of n in base 10                               %
     integer procedure digitalRoot( integer value  n ) ;
+        if n = 0 then 0
-    begin
-        integer digits, sum;
+        else begin
-        digits := abs n;
+            integer root;
-        while begin
+            root := ( abs n ) rem 9;
-            sum := 0;
+            if root = 0 then 9 else root
-            while digits > 0
+        end digitalRoot ;
-            do begin
-                sum    := sum + ( digits rem 10 );
-                digits := digits div 10
-            end % while digits > 0 % ;
-            sum > 9
-        end do digits := sum;
-        sum
-    end digitalRoot ;
     % sets p( 1 :: n ) to a sieve of primes up to n %
     procedure Eratosthenes ( logical array p( * ) ; integer value n ) ;