Set of smaller nested dolls and electronic calculator: what they have in common

1. Step 1. Set of smaller nested dolls — is part of — Matryoshka. Smaller dolls.
2. Step 2. Matryoshka — uses — Lathe. Turned on a lathe.
3. Step 3. Lathe — evolved into — Screw-cutting lathe. Maudslay added a lead screw and a slide rest.
4. Step 4. Screw-cutting lathe — has part — Gear. Change gears set the pitch of the thread.
5. Step 5. Gear — is part of — Arithmometer. Gear wheels do the counting.
6. Step 6. Arithmometer — evolved into — Electronic calculator. Electronics replaced mechanics.

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