Every Number Has a Job

You'll learnto build an actual model by giving every number in the story exactly one job.

Selection picks the family; construction writes the actual function. That means naming the quantities and their units before touching a number, then giving every number in the story exactly one slot. Read the finished model back out and each parameter should say something in the language of the situation, units attached.

8 STEPS · 6 QUICK CHECKS · SLOTS · PARAMETERS · UNITS · EXTRAPOLATION · v3

one slot per number · units travel with it

Before you start

What you're looking at

A construction template with separate slots for input, output, initial value, additive change per input unit, multiplicative factor per input unit, percentage rate, and units. The family is chosen first; only then does a number go into a slot.

The question

In this situation, which number is the initial value, and is the other one an amount added per unit or a factor multiplied per unit?

Watch for

Each parameter landing in exactly one slot, with its units traveling along.

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