[VA] Short & Sweet Math Challenge #24: "2019 Spring Special 5-tier"
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03-21-2019, 12:21 PM
Post: #2
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RE: [VA] Short & Sweet Math Challenge #24: "2019 Spring Special 5-tier"
Homage number must be divisible by 271 * 41 * 9 = 99999
Since 1e5 mod 99999 = 1, Homage number had another property: top 5 digits + bottom 5 digits = 99999 Example, since 10234 + 89765 = 99999, smallest Homage number is 10234 89765 Top digit > 0, thus 9 cases to choose. 2nd digit cannot be the first, or 9 - first, thus 10 - 2 = 8 cases ... Total Homage numbers = 9 * 8 * 6 * 4 * 2 = 3456 |
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