I do not write code without a few small tools open in the background. Three of them are documentation tabs. The other two are calculators. Below is the short list of calculators that have earned a permanent place next to my IDE.

Sanity-checking arithmetic in pull requests

When a teammate writes a percentage formula in a pricing service, I usually rerun the math myself before approving the PR. The Percentage Calculator on Equation Solver is the fastest way I have found to confirm a result without spinning up a REPL.

Quick estimates during system design

When sketching a back-of-the-envelope cost model on a whiteboard, I lean on the Compound Interest Calculator on Equation Solver to project recurring infrastructure costs over a few years — it makes the trade-offs concrete.

Frontend layout sanity checks

When a designer hands me a layout that uses 12-column grids and odd diagonals, the Pythagorean Theorem Calculator on Equation Solver helps me confirm the diagonals before I write the CSS.

Algorithm…