You have to type in a number. So if you are going to type in 1000, it would probably more likely be a successful attack if you actually forged the check so it l

You have to type in a number. So if you are going to type in 1000, it would probably more likely be a successful attack if you actually forged the check so it looked like it said 1000, so again not seeing how an adversarial example is helpful here.