Henry Ernest Dudeney/Modern Puzzles/60 - Digital Coincidences/Historical Note
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Historical Note on Modern Puzzles by Henry Ernest Dudeney: $60$ - Digital Coincidences
Martin Gardner notes that Harry Lindgren points out the fact that by inserting $9$s you can obtain answers with any number of digits:
| \(\ds 2 + 4997\) | \(=\) | \(\ds 4999\) | ||||||||||||
| \(\ds 2 \times 4997\) | \(=\) | \(\ds 9994\) |
| \(\ds 2 + 2963\) | \(=\) | \(\ds 2965\) | ||||||||||||
| \(\ds 2 \times 2963\) | \(=\) | \(\ds 5926\) |
| \(\ds 2 + 49997\) | \(=\) | \(\ds 49999\) | ||||||||||||
| \(\ds 2 \times 49997\) | \(=\) | \(\ds 99994\) |
| \(\ds 2 + 29963\) | \(=\) | \(\ds 29965\) | ||||||||||||
| \(\ds 2 \times 29963\) | \(=\) | \(\ds 59926\) |
and so on.
Sources
- 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Answers: $111$. Digital Coincidences