Did you find that the next numbers are 55 and 89?
The way to calculate the next number in the sequence is to add the previous two together. So what does this have to do with computers?
It's easy to calculate the next number in the sequence: you just have to add the last two numbers together. But what if I wanted to know the 20th number? The 50th? The 100th? That would take a long time to figure out with just pencil and paper, or even with a calculator!