In Pakistan, most of the people especially salaried persons don't know their NTN number. At the time of some documentation inquiry they need to know their National Tax Number (N-T-N) and for this they have to ask their finance person or FBR Dept. Their is a simple way to know your NTN number. How?
Here is the way... How To Find Your NTN Number in Pakistan?
You just need to go...FBR.gov.pk's Tax Payer Search
Now you just need to select CNIC from first field and then insert your CNIC number in 2nd field and submit it.
If it shows your NTN number then note it and if it show "registration not found" error then you need to contact FBR or Local Registration Officer as per these addresses.