The kind of note used in these particular measures are eight notes; they define how many beats are present in every measure. Just count how many eight notes are in each square and write the number on the top of the given time signature. Sometimes, you can't just count the eight notes because there are no eighth notes. For example, #6 has a quarter note, a quarter rest, and an eigth rest. We know that the quarter note contains two eigth notes, so that's 2, and the quarter rests have two beats, so that's another 2, and lastly, there is the eigth rest, which is one beat - in total, there are 5 beats with the eigth notes defining the rhythm.
Georges Seurat is chiefly remembered as the pioneer of the Neo-Impressionist technique commonly known as Divisionism, or Pointillism, an approach associated with a softly flickering surface of small dots or strokes of color.
