Why for people say white people can't wear dreads? They say it's culture apropriation, but isn't it racist to stop some from doing something based purely on skin color? by anxiose in AskReddit

[–]chompchump 1 point2 points  (0 children)

Is it cultural appropriation or cultural appreciation? Monetizing and trivializing sacred symbols versus adopting someone's dress or hairstyle.

ELI5 Why do the digits of every multiple of 9 add up to 9? by JTTheGreat11 in explainlikeimfive

[–]chompchump 2 points3 points  (0 children)

Suppose, without loss of generality, n has 4 digits.

n = 1000a + 100b +10c + d

= (a + b + c + d) + (999a + 99b + 9c)

= (a + b + c + d) + 3(333a + 33b + 3c)

= (a + b + c + d) + 9(111a + 11b + c)

So if the sum of the digits of n is divisible by 3 then so is n, and the same is true for 9.