My husband and I have been married for 9 years and have been satisfied with sex, but we are every three times. The last time I saw in the newspaper an expert from the British Society of Sexuality said the formula for the frequency of sex, and as soon as we calculated, we didn't meet the standard. Aren't we normal when we're only 33 years old? Can you tell me what the normal frequency of sex should be for a couple? The reader's letter surprised us. The formula of sexual frequency she mentioned was formulated by American scholars based on the influence of age factors on sexual ability. It is calculated by multiplying 10 digits of one's own age by 9 and the mother by 10 digits, which is the number of days the sexual cycle lasts, and the individual is the frequency of sex. According to this formula, the couple's sex frequency should be 3×9=27, that is, they should have sex 7 times in 20 days. Could it be that the media hype of the measure of "sex" happines...