Formula for number of sex per period of time

asdfasd

A while back, I heard that there is a formula for sex, base on the age of men, starting from 20, take the first digit of your age, multiple by 9, you get a two digit number, for instance ab, which means, you are suitable to have sex for b times every a week.

Example, if you are in the age of 20s, 2x9=18, you can do it 8 times a week
30s, 3x9=27, you can do it 7 times per every two weeks (average 3.5 per week)
40s, 4x9=36, you can do it 6 times every 3 weeks (also = twice per week)
etc.


Now, I want to know, what is the (number of time you have sex[or shots] per week) minus the (number of time you are suitable for per week).  Example, if you are in the 40s, you have sex for 3 times per week on average, but your number is 2 (b/a = 2), so then the number I want from you is 3-2 = +1.

Or if you are in the 20s, your desired number is 3.5, but if only had 2 sex[or shots] on average per week, your number is 2-3.5 = -1.5

The purpose of this is to measure the (number of times does everyone do per week) deviates from the desired number from the given formula.

asdfasd

there was a typo for " if you are in the 20s, your desired number is 3.5, but if only had 2 sex[or shots] on average per week, your number is 2-3.5 = -1.5", 3.5 should be the number for 30s, not 20s