How many protons does Manganese have?

An easy way to determine the number of protons in an atom of a given element is to check its atomic number. The atomic number of an element is the same as the number of protons in an atom of that particular element.
In the case of element manganese, the atomic number is 25. This means that an atom of manganese will contain 25 protons in its nucleus.
Similarly, we can figure out the number of neutrons present in the atom of any element. The atomic mass of an element is the weighted average of the masses of each of its isotopes. The atomic mass is roughly equal to the number of protons and neutrons (together) in an atom. For manganese, the atomic mass of the most common isotope is 55. Since the number of protons is 25, the number of neutrons in the nucleus of a manganese atom is 30 (= 55 - 25).
Hope this helps.