this trick is best performed before your guests have had too much to drink since it involves some maths calculations !
((((‘X’ x 5) + 50) x 20) + 1015) – ‘Y’
where ‘X’ = shoe size, ‘Y’ = year of birth
Step 1 – multiply your shoe size by 5
Step 2 – add 50 to total in Step 1
Step 3 – multiply total in Step 2 by 20
Step 4 – add 1015 to total in Step 3
Step 5 – subtract your year of birth from total in Step 4
Result – if maths done correctly, total in Step 5 should be your shoe size followed by your age