maths/number_of_digits.py: Streamline benchmarks (TheAlgorithms#7913)

* maths/number_of_digits.py: Streamline benchmarks

```
num_digits(262144): 6 -- 0.2226011250168085 seconds
num_digits_fast(262144): 6 -- 0.13145116699161008 seconds
num_digits_faster(262144): 6 -- 0.09273383300751448 seconds

num_digits(1125899906842624): 16 -- 0.6056742920191027 seconds
num_digits_fast(1125899906842624): 16 -- 0.15698366600554436 seconds
num_digits_faster(1125899906842624): 16 -- 0.1027024170034565 seconds

num_digits(1267650600228229401496703205376): 31 -- 1.1957934170495719 seconds
num_digits_fast(1267650600228229401496703205376): 31 -- 0.15552304196171463 seconds
num_digits_faster(1267650600228229401496703205376): 31 -- 0.13062308297958225 seconds
```

* updating DIRECTORY.md

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* Update number_of_digits.py

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 3 people

Diff for: maths/number_of_digits.py

@@ -67,93 +67,23 @@ def num_digits_faster(n: int) -> int:
 
 def benchmark() -> None:
     """
-    Benchmark code for comparing 3 functions,
-    with 3 different length int values.
+    Benchmark multiple functions, with three different length int values.
     """
-    print("\nFor small_num = ", small_num, ":")
-    print(
-        "> num_digits()",
-        "\t\tans =",
-        num_digits(small_num),
-        "\ttime =",
-        timeit("z.num_digits(z.small_num)", setup="import __main__ as z"),
-        "seconds",
-    )
-    print(
-        "> num_digits_fast()",
-        "\tans =",
-        num_digits_fast(small_num),
-        "\ttime =",
-        timeit("z.num_digits_fast(z.small_num)", setup="import __main__ as z"),
-        "seconds",
-    )
-    print(
-        "> num_digits_faster()",
-        "\tans =",
-        num_digits_faster(small_num),
-        "\ttime =",
-        timeit("z.num_digits_faster(z.small_num)", setup="import __main__ as z"),
-        "seconds",
-    )
-
-    print("\nFor medium_num = ", medium_num, ":")
-    print(
-        "> num_digits()",
-        "\t\tans =",
-        num_digits(medium_num),
-        "\ttime =",
-        timeit("z.num_digits(z.medium_num)", setup="import __main__ as z"),
-        "seconds",
-    )
-    print(
-        "> num_digits_fast()",
-        "\tans =",
-        num_digits_fast(medium_num),
-        "\ttime =",
-        timeit("z.num_digits_fast(z.medium_num)", setup="import __main__ as z"),
-        "seconds",
-    )
-    print(
-        "> num_digits_faster()",
-        "\tans =",
-        num_digits_faster(medium_num),
-        "\ttime =",
-        timeit("z.num_digits_faster(z.medium_num)", setup="import __main__ as z"),
-        "seconds",
-    )
-
-    print("\nFor large_num = ", large_num, ":")
-    print(
-        "> num_digits()",
-        "\t\tans =",
-        num_digits(large_num),
-        "\ttime =",
-        timeit("z.num_digits(z.large_num)", setup="import __main__ as z"),
-        "seconds",
-    )
-    print(
-        "> num_digits_fast()",
-        "\tans =",
-        num_digits_fast(large_num),
-        "\ttime =",
-        timeit("z.num_digits_fast(z.large_num)", setup="import __main__ as z"),
-        "seconds",
-    )
-    print(
-        "> num_digits_faster()",
-        "\tans =",
-        num_digits_faster(large_num),
-        "\ttime =",
-        timeit("z.num_digits_faster(z.large_num)", setup="import __main__ as z"),
-        "seconds",
-    )
+    from collections.abc import Callable
+
+    def benchmark_a_function(func: Callable, value: int) -> None:
+        call = f"{func.__name__}({value})"
+        timing = timeit(f"__main__.{call}", setup="import __main__")
+        print(f"{call}: {func(value)} -- {timing} seconds")
+
+    for value in (262144, 1125899906842624, 1267650600228229401496703205376):
+        for func in (num_digits, num_digits_fast, num_digits_faster):
+            benchmark_a_function(func, value)
+        print()
 
 
 if __name__ == "__main__":
-    small_num = 262144
-    medium_num = 1125899906842624
-    large_num = 1267650600228229401496703205376
-    benchmark()
     import doctest
 
     doctest.testmod()
+    benchmark()