When you add and subtract decimals do you include the zero if you have one

Why yes. 
Yes, you do include the 0. But only if it is being subtracted. 
if it is the answer if there are andy 0's at the end just take them out.
EX: 6.85600 goes to 6.856

This depends on what the problem is. If it is like example #1, where both numbers have zeroes on the ends, then you do not need to include the zero. However, if the problem is like example #2, and one number has a zero, and one does not, then you would have to include a zero on both. Just make sure that you line up your numbers correctly!

   2.50
   3.30
 +
   5.80
= 5.8

   2.8   ←(you would include a zero here)
   3.10
 +
   5.90
= 5.9

The answers 5 so there’s the you need trust me it’s right