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marte@forum.ayom.media Joined: 2024-01-06

Eu não sabia, mas existe um jeito de verificar se um número é divisível por 7 sem dividi-lo por 7.

Dado um número natural x = 10a + b, com 0 <= b < 10, o número x é divisível por 7 se e somente se o número a - 2b é divisível por 7.

Por exemplo, o número 861 é divisível por 7?

861 = 10(86) + 1, em que a = 86 e b = 1.

86-(2 x 1) = 84 e 84 = 7 x 12.

Logo, 861 é divisível por 7.

Welcome to the nostalgia-filled piefed instance of yesteryear.

Open Registration with Application questionnaire.

If you have a question or comment you can post in !meta@retrofed.com or message @DosDude@retrofed.com or @Die4Ever@retrofed.com

In case of downtime and/or emergency, we will post updates on @DosDude@mastodon.social

Some rules we try to uphold:

Be civil. Bigotry is not welcome. This includes (but is not limited to): transphobia, queerphobia, racism, ageism and ableism. We do not promote hate.
Communities need to be Retro or Retro-adjacent.
Please don't upload pornographic content. (use an external image host for that)