this post was submitted on 09 Nov 2023
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[–] [email protected] 55 points 1 year ago (1 children)

29% of 29 is 29% of 29

Fuck, this trick sucks.

[–] [email protected] 2 points 1 year ago* (last edited 1 year ago) (1 children)

Which equals 29^2 x .01 => ((28 x 30) +1) X .01
=> (840 + 1) x .01 => 8.41

28 x 30 is an easy mental calculation, as is adding 1, as is moving the decimal place over 2 places. I am teaching this to 4th graders, in two weeks. % to decimal is next week. They can square 2-digit numbers in their heads, already.

[–] [email protected] 5 points 1 year ago* (last edited 1 year ago)

((30 x 30)-30-29) x .01, easy