Magic numbers

Magic numbers are number that contains 6 or 8, but not both.

So, the following are magic numbers: 6, 8, 666, 888, 106, 1623, 1457864

And the following aren't magic numbers: 68, 1086, 6008, 346893, 0348644

Now, find the count of magic number within a range. So the count within the range 1 - 10 is 2 and the count for the range 1 - 100 is 34.

Question: What is the count of magic numbers for the range 1 - 1,000,000,000?

PS: I was asked this question for an interview. I was given 8 test cases the first 6 could easily be solved computationally, but the last two were for the ranges 11,000,000,000 1 - 1,000,000,000 and 12521 - 2^{52} are unlikely to be solve computationally.

#NumberTheory

Note by Premal Nayee
1 year, 1 month ago

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Comments

I estimate 100 - 10,000 magic numbers.

A Former Brilliant Member - 1 year, 1 month ago
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