wpf controls - Why is WPF slider value not precise -

i have slider in wpf

<slider x:name="slider" maximum="8" minimum="1" verticalalignment="center" tickfrequency=".1" issnaptotickenabled="true" tickplacement="topleft" smallchange="0.1" /> 

to value have bounded label

<label content="{binding value, elementname=slider}"/> 

as set focus on slider , move right, or drag thumb mouse, value gets raised 0.1 expected, shows kind of value 1.7000000002

does know how fix show values 1.1, 1.2 etc? thanks

why don't use textblock instead of label?

<textblock text="{binding value, elementname=slider}"/>

display slider's value want.