Several numbers less than 20 can be added together to produce a sum that's divisible by 5.
Let's explore some examples, keeping in mind we're looking for numbers and not necessarily prime numbers (as the reference mistakenly suggests):
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Single Number: 5, 10, 15 (These are trivially divisible by 5)
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Two Numbers:
- 1 + 4 = 5
- 2 + 3 = 5
- 1 + 9 = 10
- 2 + 8 = 10
- 3 + 7 = 10
- 4 + 6 = 10
- 5 + 5 = 10
- 1 + 14 = 15
- 2 + 13 = 15
- 3 + 12 = 15
- 4 + 11 = 15
- 5 + 10 = 15
- 6 + 9 = 15
- 7 + 8 = 15
- 1 + 19 = 20
- 2 + 18 = 20
- 3 + 17 = 20
- 4 + 16 = 20
- 5 + 15 = 20
- 6 + 14 = 20
- 7 + 13 = 20
- 8 + 12 = 20
- 9 + 11 = 20
- 10 + 10 = 20
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Three Numbers:
- 1 + 1 + 3 = 5
- 1 + 2 + 2 = 5
- ... many more combinations exist
In summary, many numbers less than 20, when added together (alone, in pairs, or in groups), can produce a sum that is divisible by 5.
