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Advent calendar 2025
24 December
All 2025 advent puzzles
~
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3 and 5 are both factors of 2025, and 3 and 5 are the only two prime numbers that are factors of 2025.
What is the largest three-digit number that has both 3 and 5 as factors and no other prime numbers as factors?
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The other three digit numbers that have 3 and 5 as factors and no other prime factors are:
3
1
×5
3
= 375
3
2
×5
2
= 225
3
3
×5
1
= 135
3
3
×5
2
=
675
3
4
×5
1
= 405
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the only crossnumber
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