你应该首先将字符串combobox1.text转换成双重字符串：



Convert.ToDouble Method（String）（System） [ ^

combobox1.text * textbox1.text * Random(0.177-0.325) * (1 + combobox2.text * 0.05) * (1 + combobox3.text * 0.3)

Combobox items are numbers 0-25, for example.

What I have tried:

It returns a 0 every time... I am not sure why. I am not good at this stuff.

You should convert the string combobox1.text to a double first:

Convert.ToDouble Method (String) (System)[^]