So a full circle is 360 degrees. 90 degrees is 1/4 of that. SO you can either add 90 to itself till your at 360, or multiply, 90 x1, 90 x2, and you will find out that because it is 1/4 your answer is 4!!! I hope this helps, is possible maybe a thanks and brainliest!!!(Im trying to get to the next rank!)