GeekDad Puzzle of the Week Solution – Palindromic Products

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This week’s puzzle, as previously posted:

The smallest three-digit palindromic product of two, two-digits numbers happens to be a perfect square: 11 x 11 = 121. The largest three-digit palindromic product of two, two-digits numbers is 999 = 37 x 27, and the smallest four-digit palindromic product of two, two-digit numbers is 1001 = 91 x 11. The largest four-digit palindromic product of two, two-digit numbers? 91 x 99 = 9009.

Palindromic numbers from around the interwebs.
Palindromic numbers from around the interwebs.

This week’s Geekdad Puzzle of the Week is straightforward: What are the largest and smallest palindromic products of the appropriate set of digit-sizes for each of three, four, and five-digit numbers? Note that like two-digits numbers, above, there may be more than one digit-size applicable.

Congratulations to Blaine for submitting one of the many correct answers to this week’s puzzle. The coveted $50 ThinkGeek Gift Certificate for this week will bear his favored name!

Here is the list of multiplicands and products that fill out each digit combination possible.

Multiplicand DigitsMultiplicandsPalindromic
Product
Product Digits
211 x 111213
27 x 37999
13 x 7710014
91 x 999009
3101 x 101102015
271 x 36999999
143 x 7071011016
913 x 993906609
41001 x 100110020017
2151 x 46499999999
1781 x 5621100110018
1507 x 664310011001
9901 x 999999000099
510001 x 100011000200019
16667 x 59997999969999
19999 x 50001999969999
19019 x 52579100000000110
99681 x 999799966006699

Thanks to everyone that reads and participates with these puzzles. Happy puzzling!

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