90/90 = 100%
A fraction like 90/90 represents a complete amount, so it equals 100%. You might see this when all 90 seats in a theater are filled, every question on a 90-question quiz is answered correctly, or a project is fully finished.
You can picture 90/90 as one whole circle shaded in, with no empty space left. Since the top and bottom numbers are the same, you can quickly estimate that the value is the entire amount rather than part of it.
A common mistake is thinking the large numbers make the fraction larger than one whole. The numbers may be big, but because the numerator and denominator match, the fraction still represents exactly one whole, not 90 wholes.
