Reduce allocations and formatting

src/Julia/Problems001-050/Problem012.jl

@@ -33,17 +33,17 @@ function Problem12()
     What is the value of the first triangle number to have over five hundred
     divisors? =#
 
-    function num_divisors(n)
-        r = isqrt(n)
-        2 * count(n % i == 0 for i in 1:r) - (r^2 == n)
+    function num_divisors(number::Int64)
+        res = isqrt(number)
+        return 2 * count(number % i == 0 for i = 1:res) - (res^2 == number)
     end
 
 
-    triangle = 0
-    for i in Iterators.countfrom(1)
-        triangle += i
-        if num_divisors(triangle) > 500
-            return string(triangle)
+    ans::Int64 = 0
+    for number in Iterators.countfrom(1)
+        ans += number
+        if num_divisors(ans) > 500
+            return ans
         end
     end
 end