When overloading, what priority is the overload called?

[zms9110750]

I have a class to help me customize the format to numbers

public struct Float : IFormattable
{
	float value;
	public override string ToString() => ToString(null, null);
	public string ToString(string format, IFormatProvider formatProvider)...

	public static implicit operator Float(float f)
	{
		return new Float { value = f };
	}
	public static implicit operator float(Float f)
	{
		return f.value;
	}
}

Why doesn't he think that my parameter is of type object, but he implicitly converts it to float, and then uses float overloading?

Float f = 12345678;
Console.WriteLine(f.ToString());		//12.3M
Console.WriteLine(f);				//123456789
Console.WriteLine($"{f}");			//12.3M

[CyrusNajmabadi]

Overload resolution is specified here: https://github.com/dotnet/csharpstandard/blob/standard-v6/standard/expressions.md#1164-overload-resolution

[CyrusNajmabadi]

The parts of relevance are:

Given an argument list A with a set of argument expressions {E₁, E₂, ..., Eᵥ} and two applicable function members Mᵥ and Mₓ 
with parameter types {P₁, P₂, ..., Pᵥ} and {Q₁, Q₂, ..., Qᵥ}, Mᵥ is defined to be a better function member than Mₓ if

for each argument, the implicit conversion from Eᵥ to Qᵥ is not better than the implicit conversion from Eᵥ to Pᵥ, and
for at least one argument, the conversion from Eᵥ to Pᵥ is better than the conversion from Eᵥ to Qᵥ.

So the question is whether the conversion of Float to float is better than the conversion from Float to object.

THis is determined here: https://github.com/dotnet/csharpstandard/blob/standard-v6/standard/expressions.md#11646-better-conversion-target

Given two types T₁ and T₂, T₁ is a better conversion target than T₂ if one of the following holds:
An implicit conversion from T₁ to T₂ exists and no implicit conversion from T₂ to T₁ exists 

So here we have float and object as conversion targets. float is considered better as there is an implicit conversion from float to object but no implicit conversion from object to float.

Put another way, float seems like a more precise/narrow/specific match, and object is a less precise/wider/less-specific match. We prefer the more precise one, and so the float overload is preferred.