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Joined 1 year ago
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Cake day: June 19th, 2023

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  • It works differently for each number. For 2, the last number has to be divisible by 2. For 3, the sum of the digits has to be divisible by 3 For 5, the number has to end with a 0 or a 5. For 7, it is kinda tricky. Take the last digit, double it, and subtract it from the numbers on the left. If the remainder is 0 or divisible by 7, the whole number is divisible by 7. For example 49: 9×2=18, 4-18=-14, -14/7=2 with remainder 0. For 700, 0×2=0, 70-0=70, 70/7=10 remainder 0.

    This is usually specified for prime numbers, for non-prime number, you just do calculate the prime components of a number and combine the rules.

    For example, divisibility by 15: it has to be divisible by 3 and 5. 1+5=6, 6/3=2 remainder 0. 15 ends with a 5. For number where with multiple same prime components the rules for these duplicate numbers have to apply multiple times. Like for 25, it has to end with a 5 or 0, and when dividing the number by 5, the result has to end with a 5 or a 0 aswell.








  • This website is deprecated.

    It’s kept around mainly for historical reasons.

    I’ve tried Docker Swarm because Kubernetes seemed like an overkill for a cluster of 4 small-ish servers. There have been several issues (networking for example) that took me two days to solve - by reinstalling the machine completely.

    There are some hoops and hurdles along the way, some command will just literally brick your cluster without any notice whatsoever (like removing the second manager, leaving only one and cluster stops responding, but you get no warning that’s gonna happen).

    Also secrets, where there is no simple way to manage them, or replace them. You can’t just replace a secret, you have to remove and recreate it. Which means turning off the service or creating a new secret with a different name and do a rolling update, which is just annoying to do every time unless you can afford a robust CI CD pipeline code that does it automatically.