When someone handed you a calculator for the first time, it meant that long division was never going to be required of you ever again. A huge savings in time, a decrease in the cognitive load of decision making.
You can use that surplus to play video games and hang out.
Or you can use that surplus to go learn how to do something that can't be done by someone merely because she has a calculator.
Either way, your career as a long-divisionator was over.
Entire professions and industries are disrupted by the free work and shortcuts that are produced by the connection economy, by access to information, by robots. Significant parts of your job are almost certainly among them.
Now that we can get what you used to do really quickly and cheaply from someone else, you can either insist that you still get to do that for us at the same fee you used to charge, or you can move up the ladder and do something we can't do without you.