By default, the Mathematica Front End displays 6 digits of numbers with finite precision. It is internally using more digits for the calculations, but it only displays 6, rounding the final digit if necessary.

You can changed this by going to File>Preferences (Mathematica>Preferences on a Mac), choosing the Appearance tab, the Numbers subtab, and then the Formatting sub-subtab. A bit over halfway down, there is an option for "Number of digits displayed in output". Change this to something greater than 6. You will then see your desired result in the Front End.

You can use functions like NumberForm to change how numbers are displayed on a case by case basis, if needed.