Why do simple math operations on floating point return unexpected (inaccurate) results in VB.Net and Python?

Question

x = 4.2 - 0.1  

vb.net gives 4.1000000000000005
python gives 4.1000000000000005

Excel gives 4.1<

Answer 1

In vb.net, you can avoid this problem by using Decimal type instead:

Dim x As Decimal = 4.2D - 0.1D

The result is 4.1 .