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Here's my one weird trick: work toward a PhD in mathematics, then get a postdoc, where you finally get assigned to teach courses like upper division undergradua
by kmill 5y ago
Here's my one weird trick: work toward a PhD in mathematics, then get a postdoc, where you finally get assigned to teach courses like upper division undergraduate number theory. Thanks to this experience, I can tell you immediately what the factors of numbers like 6 and 15 are. 72 still takes some thinking, though.
- marginalia_nu 5y agoMy physics education just has me aggressively rounding toward the nearest easy calculation while keeping the error term in my pocket. 72/3 = 60/3 + error ~= 20 (it's 24) 72/4 = 80/4 - error ~= 20 (it's 18) 72/5 = 80/5 - error ~= 16 (it's 14.4) 72/6 = 60/6 + error ~= 10 (it's 12) For ballpark estimations on the back of an envelope, it can go a surprisingly long way.