The current intensity is the product between the total charge that flows through a certain point (in our case, the target) in a time interval

:

We know the current,

, and the time interval,

, so we can find the total charge:

The total charge Q is the product between the number of protons N and the charge of each protons, e, which is

:

we can re-write the equation solving for N, so we can find the number of protons striking the target in 17 s:
