The phrase "reason number" refers to a particular or specific explanation or cause for something. It helps identify and understand the main factors behind a situation or decision. Full definition
Here are five perfectly normal and common reasons your number on the scale might read higher than expected. (bodybuilding.com)
For religious and cultural reasons The number one question on Ask the Muslim Girl is about relationships! (myintimcity.com)
By her own reasoning the number should actually be higher, since there are probably a large number of midwives that «dump» a patient and the hospital takes up the slack. (skepticalob.com)