Method 1 of 3: Deducing Someone's Age Using a Selected Number Ask your friend to choose a number between two and ten. ... Multiply the given number by two. You can do this math by hand or your friend can use a calculator for the rest of the trick. Add five to the answer. ... Multiply that number by 50. ... Ask your friend if they've already celebrated their birthday for this year. ... Subtract the year that they were born. More items...How do you calculate the age of a person?
Assuming a birthdate is in cell B2, the formula to calculate age in years goes as follows: =(TODAY()-B2)/365. The first part of the formula (TODAY()-B2) returns the difference between the current date and date of birth is days, and then you divide that number by 365 to get the numbers of years.