I want to know what not integer numbers means in this case? if $30$ days $= 4$ weeks and $2$ days $4.2$
then why $20$ days does not correspond to $2$ weeks and $8$days $4,8$?
being that: $\frac{30}{7} =$ $4.28571428571$ and $\frac{20}{7} = 2.85714285714$