1- Take a calculator.
2- tell the person to take a 4 digit number and place in on the calculator ( 5 and 6 digits work too)
3- u tell them to do the following steps and enter their year of birth...and then you tell them to press = and give you the calculator.
4- you subtract 1759
and you get the 4 digit number chosen + age.
That's how you get their age without them declaring it themselves to you...and without them actually declaring what their year of birth is