Public admission time.

I work in finance but failed arithmetic at school (no wonder we had a GFC). I am not talking about algebra, calculus, etc just arithmetic.

I understand the sensor size and crop factor on SLR sensors but with compact and bridge cameras we get sensor sizes like 4/3”, 2/3”, ½”, etc.

I also understand that these smaller sensors are 5, 6 or 7 times approximately smaller than a FF sensor. I simply divide the smaller size lens focal length into the FF equivalent provided in the specs to get his result.

BUT

How do the fractions in the second paragraph above translate to “x – times” smaller sensor?

Ps. Please keep my maths problem a secret.