Had a school homework problem: Find the last 3 digits of 7^9999. We were supposed to try manually and see that it was periodic. Instead I used my home computer.

Had a school homework problem: Find the last 3 digits of 7^9999. We were supposed to try manually and see that it was periodic. Instead I used my home computer. I had 12 Kb of memory, so using 1 byte for each digit I could have the result in memory once. I did the multiply by seven with seven additions, as the CPU didn't have multiply instructions. (RCA 1802, if you are curious). I managed to get the result, saved it on a cassette tape, and went to see a friend who had a printer. Printed the number out, if I remember right it was about 3 pages long. Drew a circle around the last three digits, and showed to my teacher. She was suitably impressed.