fix(biohash): Double.GetDigit() users math only again

Exact same formula it originally had but without using Simba functions. Thanks slacky!

utils/math.simba

@@ -11,8 +11,7 @@ This file has math related methods.
 (*
 ## Double.GetDigit
 ```pascal
-function Double.GetDigit(n: Int32): Int32;
-function Double.GetDigit(n: Int64): Int64; overload;
+function Double.GetDigit(n: Int32): Integer;
 ```
 Get the digit at the **n** place of the Double.
 
@@ -25,25 +24,9 @@ begin
 end;
 ```
 *)
-function Double.GetDigit(n: Int32): Int32;
-var
-  i: Int32;
-  str: String;
-begin
-  str := ToStr(Self).Replace('.', '');
-  if Length(str) = 0 then Exit;
-  if not InRange(Inc(n), 1, Length(str)) then Exit;
-  Result := StrToInt(str[n]);
-end;
-
-function Double.GetDigit(n: Int64): Int64; overload;
-var
-  str: String;
+function Double.GetDigit(n: Int32): Integer;
 begin
-  str := ToStr(Self).Replace('.', '');
-  if Length(str) = 0 then Exit;
-  if not InRange(Inc(n), 1, Length(str)) then Exit;
-  Result := StrToInt64(str[n]);
+  Result := Trunc(Self*10**(n+1)) mod 10;
 end;
 
 (*
@@ -52,7 +35,6 @@ end;
 function NumberPerHour(n: Int64): Int32;
 function NumberPerHour(n: Double): Int32; overload;
 ```
-
 Calculate how many **n** per hour. You can optionally specify the amount of **time** to use in the calculation.
 
 Example: