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+--
+--  Project Euler problem #10
+--
+--  The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
+--
+--  Find the sum of all the primes below two million.
+--
+
+with Ada.Numerics.Elementary_Functions,
+     Ada.Text_IO;
+
+use Ada.Numerics.Elementary_Functions,
+    Ada.Text_IO;
+
+procedure Ten is
+    subtype Long_Natural is Long_Integer range 0 .. Long_Integer'Last;
+    Ceiling : constant Natural := 2_000_000;
+    Result : Long_Natural := 0;
+
+    function Is_Prime (Input : in Natural) return Boolean is
+        -- Using the "Trial Division" method detailed in this Wikipedia entry:
+        -- https://secure.wikimedia.org/wikipedia/en/wiki/Prime_number#Trial_division
+        Boundary : constant Natural := Natural (Sqrt (Float (Input)));
+    begin
+        for Index in 2 .. Boundary loop
+            if (Input mod Index) = 0 then
+                return false;
+            end if;
+        end loop;
+        return true;
+    end Is_Prime;
+begin
+    for Index in 2 .. Ceiling loop
+        if Is_Prime (Index) then
+            Result := (Result + Long_Natural (Index));
+        end if;
+    end loop;
+    Put_Line ("Sum of all primes:" & Long_Natural'Image (Result));
+end Ten;