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The Definitive List of So-called Rules That Add Up to 100

ClearerThinking founder Spencer Greenberg is a mathematician by training, and like most mathematicians, he likes to play with numbers. He recently compiled this list of 16 rules about life, work, interpersonal relationships, and maritime law — all of which feature proportions that add up to 100. We thought you'd get a kick out of reading them; some are serious and some are silly, but you'll definitely learn something along the way.

  • The 100/0 rule: You should be 100% certain 0% of the time.

  • The 80/20 rule: 80% of all output comes from 20% of all effort (not literally true, but true in spirit most of the time).

  • The 77/23 rule: The poorest 77% of the world’s population accounts for approximately 23% of the world’s income (GDP figures 2010).

  • The 75/25 rule: In maritime law, no more than 25% of the total unlicensed seamen on board a documented vessel shall be aliens lawfully admitted to the United States for permanent residence.

  • The 70/30 rule: If you’re trying to persuade someone, spend 70% of the time listening and only 30% of the time talking (so as to deeply understand the other person’s perspective, goals and incentives, and to make sure they feel deeply understood).

  • The 70/20/10 rule: Devote 70% of your efforts to the work that you already know how to do and are good at, 20% to other opportunities for growth that you're confident are a good idea, and 10% to more speculative or ambitious challenges.

  • The 60/40 rule: In relationships, both parties should aim to put in 60% of the work and only expect to get 40% back. Or, put another way: if you think you’re doing half the work in a relationship, you’re probably doing less than half, so plan to do what feels like 60% to you.

  • The 50/50 rule: In conversation, you should spend about half the time listening and about half the time talking. I.e. if you’re talking far more than this, you might be hogging the conversation or annoying your conversation partner; if you’re talking far less than this, you may be creating extra work or stress for your conversation partner.

  • The 40/60 rule: If you’re trying to build a brand, spend only 40% of your work time creating content, and 60% of your time promoting it.

  • The 30/70 rule: If you run an organization, you should spend 30% of your time working on leading the organization in new initiatives, and the remaining 70% managing the execution of existing initiatives.

  • The 25/69/6 rule: 25% of the rules on this list were written by me for the purpose of this post; 69% were cooked up by others in order to sell books or make their ideas easier to remember; 6% are regulations about seamen.

  • The 10/90 rule: 10% of what your experience of life is determined by what happens to you; 90% is determined by how you react to and think about what happens to you.

  • The 3/97 rule: If you spend 3 years working your ass off at something, you can become better than at least 97% of people in the world at it.

  • The 1/99 rule: 1% of the artists (or musicians) make 99% of the money.

  • The 1/9/90 rule: In online communities, 1% of users contribute most of the activity, 9% of users each contribute a little bit of activity, and 90% are lurkers who never contribute.

  • The 0/100 rule: 0% of the rules on this list are 100% true, but 100% of the rules on this list are more than 0% true (except perhaps this one!).

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