HP as calculator

Riiinnngggg.... The office bell rang. Its time to go home! But not for me, I was to go for my third lesson of my CAT course. I rushed out and in my hassle I forgot to bring my pen and calculator to class! I went for dinner at BK, reached SAA, got into class, sat down and opened my bag, I realized that I forgot to bring all the necessary items, namely pen and calculator! Immediately, I asked my classmate for a pen and guess what? I used my HP as my calculator for the entire lesson! When I was doing calculation with my HP, the teacher thought that I was SMSing in his class, but the fact was that I was doing calculation. He was walking around when we were doing Trading, Profit & Loss for a question, he approached the place where I was sitting, with the intention of asking me not to SMS in class(or so I thought). Little did he realized that I was doing calculations using my HP! When he saw it he smiled and let me off. He couldn't stop smiling at me throughout the entire lesson. A few of my classmates were amused that he kept smiling at me throughout the entire lesson and asked me what had happened when we were walking to the MRT station. I told them that I used my HP to do calculations as I forgot to bring my calculator and pen to class. They were having a good laugh over my encounter till they reached their destination station. Remind me never to forget such important things again...