42/84 as a percentage is 50.00%. This tells you that the fraction represents exactly half of a whole.
The fraction 42/84 can be reduced to its simplest form, which is 1/2. When you think of a pie cut into two equal parts, each part is 50 % of the pie.
In everyday use, you might see this percentage on a test score, a discount, or a measurement. Knowing that 42/84 equals 50.00% helps you quickly understand that something is right in the middle of the scale.