Why not just get a timer? I know some people will have a timer next to them set at the same speed as lotto

 

I don't really want to lug around a bunch of accessories. Calculator, timer, ect ect ect

 

It just be like a small simple cooking timer, if you have an iPhone (Not sure about droids or other smartphones) you could just set the timer at 15 mins, and this is only if you play lotto a lot like me.