I started to search more and more. I hoped the the battery was somewhere in the cupboard, where I had last put it. I saw the cupboard door open. Maybe I left it open, I thought to myself, and I opened the cupboard door. There was no battery. I knew that the person would starve if left him/her alone, and I also knew the portal would close soon. The portals have a timing device and automatically close after some time. I needed to build another battery now. I knew that if I clipped together some 9-volt batteries, I could potentially receive enough power to fire off one portal. I needed about 7000 volts to do this. I did some calculations, and figured out I needed about 200 batteries to do this. I had exactly 10 batteries. I also had a 10-hour time limit.