That is a very common error of young native speakers learning to write – I could write „en” where „ę” should be as late as 5th grade and I sometimes do that still(rarely though), when writing very fast(for example on internet chats). :)
But actually shouldn't because the best English translation is "A man", not "The man". So we do not have "the" which could be understood as "this" and therefore translated as "ten" -> and "Pan je jabłko" on its own means "You're eating an apple, sir".
If you're on a PC, I like Microsoft's PLP - Polish programmers keyboard add-in: all the letters where they are on your QWERTY keyboard but with accents on the ALT GR key, so you don't have to learn a whole new keyboard layout without being able to see it.