There are many ways of checking that blade is 90 degrees to table. Here is my favorite method. It requires no measuring tools, just a scrap of wood. Cut the piece of wood in half, then flip one half over and butt the cut ends together while pushing the two halves against a straight edge such as the fence. If the blade is not at 90 degrees to table, the cut ends will not butt together evenly.
Demonstrated in video. https://youtu.be/uZu1VPtX8VE​