GST Number Definition
For each tax payer registered under GST, the GST number or GSTIN is a unique 15-digit number. Through registering under GST, you can get your GST number or GSTIN.
The first 2 digit GST number represents the state of registration of the tax payer. The next 10 letters are the tax payer's PAN number. The next 2 digits are for the code of the organization and the last digit is the check sum number.