Pf Pension calculation formula

Dear All,
I have a small doubt in Pf Pension calculation formula.
Please explain the doubt i have
that is Formula is Average salary X No.of year service / 70.
"Why 70 is taken for dividing."
Regards
Rajesh S

70 is nothing but a math figure only
Labor department makes ensure that the employee can work max 35 yrs and pension would be 50% of the last wages , so 35 /70 formula is applied, there are many more catches within the scheme but 70 is just a number to get the percentile of the payable amount