c# Unexpected numbers in double variable in for loop

Question

for (double i = 0; i < 0.05; i+= 0.001)
{
            //do something
}

In this for loop,

I thought the count would go as follows: 0, 0.001, 0.002, 0.003, etc., but it becomes 0.0090000000000000011 instead of 0.009.

Why is such conversion possible?

Answer 1

The resolution of the double/float is not infinite.

See here

Because some numbers cannot be represented exactly as fractional binary values, floating-point numbers can only approximate real numbers.