Small coin cell battery and hollerith tabulator: what they have in common

1. Step 1. Small coin cell battery — is part of — Continuous glucose monitoring. Power.
2. Step 2. Continuous glucose monitoring — is used in — Insulin pump. A closed-loop system.
3. Step 3. Insulin pump — has part — Servomotor. A stepper motor moves the plunger.
4. Step 4. Servomotor — uses — Electromagnetism. A servo is an electric motor with feedback.
5. Step 5. Electromagnetism — is used in — Hollerith tabulator. The counters click with electromagnets.

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