Tool

One small thing that computes.

For when The answer has a parameter in it: it turns on numbers only the reader has, or on data they should not hand to anyone, and the useful thing is either the feel of how the answer moves or the fact that nothing left their machine.

Three examples

• A model you drive, where the answer is not proportionalHow many people the desk needs, and what happens when one is off
• A chart with the whole table under it, and the arithmetic exactWhat an extra $200 a month takes off a mortgage
• The reader's own data, and the reason it is a page at allWhat is on repeat, out of a statement you paste in