Score multiplier

I need help designing a score multiplier for an endless 2d runner. How it’s suppose to work is if you deliver to customers in succession your multiplier goes up by one. However if you miss a customer your multiplier resets. It seems easy but I’m new to programming and could use some help.

It is easy. C# version.

float score = 100;
float multiplier = 1.0f;
float finalScore = 0;

multiplier += 1.2f; // Succession
multiplier -= 0.4f; // Failure or whatever you want.

finalScore = score * multiplier;