If you're wanting to test your reaction time for the calculator, you can do so here by playing this game. Just try to hit the brakes when the light turns red.
Because we're dealing with reaction times between the pedals in a car, this test done by mouse or touch screen may not give an accurate representation of reaction time. This game tests your reaction time as an estimate only.
Reaction times will vary with age, tiredness, distractions, impairment with alcohol or drugs and many other reasons.
Click the "start" button to turn the lamp green. Wait until the lamp turns red and the brake button appears and try and click the brakes as fast as you can.