Difference between two dates in months

I can find formulae within excel help to calculate the number of days, months or years between two dates, but they don't quite do what I'm after.

I need to know how old someone was at the time they answered a questionnaire in months, but I don't want it to round up to the nearest month.

For example, if I use the formulae
=(YEAR(A4)-YEAR(A3))*12+MONTH(A4)-MONTH(A3)
for the Date of birth
10/05/1990
and the date of questionnaire of
8/05/2000
I can answer of 120 months, which is 10 years.

However, they are not 10 years old yet, and for the purpose of my analysis I need this to be recorded as 119 months.

Is there another formulae someone can suggest?

Thanks

Brilliant thanks! Tested it and it gives me 119 as I wanted.