Question

how many particles are in an electron?

Answer 1

None - an electron, unlike a proton or a neutron, is a fundamental particle.

Answer 2

It is now believed that protons and neutrons (which constitute nuclei of ordinary matter) are themselves built out of more elementary units called quarks. A proton and a neutron consist of three quarks each. Two types of quarks, the so called ‘up’ quark (denoted by u) of charge + (2/3) e, and the ‘down’ quark (denoted by d) of charge (–1/3) e, together with electrons build up ordinary matter. (Quarks of other types have also been found which give rise to different unusual varieties of matter.) so e- will be 3 down quarks :)

Answer 3

An Electron is NOT made of quarks. Electrons are fundamental particles, just as quarks are. There are, in total, about 16 fundamental particles.