When I enter a single digit in a cell, it lists multiple digits

Question

I wish to type a number into a single cell.  If the number has multiple digits like 123 (for example), the cell accepts it just fine.  However, sometimes I need to enter just a single digit number into the cell, such as a 5 (for example).  When I enter in 5, it does not accept it, and it has a very long string of numbers pop up in a window within the cell, and sometimes it even has a + sign and even a letter pop up at the end of the string.  The only way to get rid of the long string of numbers is to add a 0 in front of the 5.  However, I don't want to have to add a 0 in front of it every time. 
any help would be appreciated. 
Thanks!!  Midnight

Answer 1

     Here is where I try to insert a 1 in the cell under JAN
     If I type in 1 and hit enter, it gives me this weird figure, with a plus sign.
Again, thank you for your help.
Midnight