What is a model in mathematics with examples

To obtain the probability of obtaining heads at least 3 times out of 5 times we recall that in her simulation she assigned odd digits to represent heads and even digits to represent tails. Thus, we count the simulated numbers to see in how many numbers do we have 3 or more odd digits.

Below, the simulated numbers with 3 or more odd digits are bolded.
 32766 53855 34591 27732
47406 31022 25144 72662
03087 35521 26658 81704
56212 72345 44019 65311

We have 6 simulated numbers having 3 or more odd digits.
Therefore, P("heads" at least 3 out of 5 times) = 6 / 16 = 3 / 8.