Answer:
4
Step-by-step explanation:
Quarter notes are worth one count (the black filled in notes), and half notes are worth 2 counts (the notes that aren't filled in). The last note in the measure is a whole note, which is worth four counts. You could also look at the time signature at the beginning of the song, that says 4/4. I'm an intermediate piano player and I have been playing piano for 6 years, so don't worry. Hope this helps!