 :::Hi.  Actually in Iran 96% understand Persian (according to Hamshahri newspaper and 98% in Tehran).  It is the native language (if you include subdialects like Gilaki, Mazandarani, Lur) of 65%.  But for the purpose of argument if you include standard Tehrani Persian it is 51% according to CIA factbook.  So that is 35 million.  Now take Afghanistan 50% (CIA factbook) is native.  that is 15 million right there.  So you are above 50 million.  Finally Tajikistan and Tajiks in the USSR (according to some sources 40% of Uzbekistan is Tajik) and Afghan refugees in Pakistan easily numbers 10 million.  So 60 million is actually very low end estimate.   