Similarly, I have used dc as my desktop calculator of choice since the mid-90s. It has been useful in many one-liner scripts too. A simple, powerful tool.
One-liners? dc is using reverse Polish, with newlines to separate tokens, or is there an alternate separator I didn't know all these years?
tokens are separated on parsed input, where the token needs to be explicit, like two numbers in a row a space can separate them. An example from the manual. the first ten values of n!