Find out how old your Dad's new girlfriend really is.

Here is a formula that will let you find out how old someone is without them knowing.

Ask the person to write down the number of the month they were born (September=9)

double that number
add 5
multiply by 50
add their current age
subtract 365

then have them tell you the number they came up with

in your head add 115 and you will have a number which shows the month and year they were born.

example 1045 = October and 45 years old