Index card and Babbage’s Analytical Engine: what they have in common

1. Step 1. Index card — is part of — Index card. A stiff card of standard size.
2. Step 2. Index card — is made of — Paper. Paper.
3. Step 3. Paper — is material for — Punched card. Punched cards are stiff card.
4. Step 4. Punched card — is used in — Babbage’s Analytical Engine. Operations and numbers were entered on punched cards.

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