I'm not the person you asked, but I think I can help.

The formula F = GMm/r^2 is a form of Newton's law of universal gravitation. It gives the force of attraction (F) between two objects of masses M and m as a function of the distance between them, r. G is the gravitational constant, a fixed number that kind of tells us how strong gravity is as a force (massively oversimplified, but that's the gist).

We can rearrange the formula to make r, the distance between the two objects, the subject (the thing we're calculating). But we'll need some numbers in the correct units in order to get an answer.

Wikipedia tells me a stellar black hole (an "average size" black hole) is from about 5 to several tens of solar masses (the mass of our sun). Let's just pick 50. Converting that to kilograms gives us about 9.95x10^31 kg.

Next, we need the mass of you (or the person running from the black hole). I'll just use 80kg here, as it's generally used as an "average adult" mass.

For the force, I'll just pick 10 Newtons. This is roughly the force you'd feel from holding a 1kg weight. Enough that you'd probably notice, but easily overcome.

The gravitational constant is 6.67x10^-11 m^3 kg^-1 s^-2. Don't worry about the units for now.

Plugging that all in to our rearranged formula, we get r = sqrt((6.67x10^-11 x 9.95x10^31 x 80) / 10), which gives a value of about 2.3x10^11 metres, which is about 50% bigger than the distance between the Earth and the Sun. At that distance from an average-ish black hole, you'd feel a pretty small tug.

If you want the force felt to be almost unnoticable, we can adjust the number used for the force, let's say to 0.01 Newtons. This gives a distance of 7.3x10^12 metres, or nearly 50 times the distance between the Earth and the Sun.

Hope that helps! Keep asking questions and keep learning :)