This means that input textbox is empty. So in designer view set textbox to accept only numbers and set textbox text to 0 so in case someone click's button without setting a number you won't get any error
Or another way is to check if textbox text is empty then show alert else proceed with procedure
@ABG Sheer coincidence indeed? To be honest, I got this idea from watching the same video. I actually follow these cool channels and had watched it 2 weeks ago. I won't say that I didn't know about the Conjecture before, it's just that I never bothered to think about it. Only a few days ago, I got the idea to create an app for it. They told in the video that it has been tested by brute force by computer programs made by brainy people. I don't disagree with the fact that it has been tested till 2^68, I thought it would be nice to check it out myself ( rather via my program ).