#mathe #FediLZMathe #mentalmath #MentalMathMonday ##WieRechnestDu so, hier einmal @howie_hua in Action mit der gestrigen Kopfrechenidee https://www.tiktok.com/@howie_hua/video/7243802628885433646

that's your #mentalmath

"Word riddles at the public library" https://www.youtube.com/watch?v=EvSxhyJhfM8

Fun questions to ask nieces, nephews, grandkids -- and other nice people -- at Thanksgiving -- or any other time of year. Encourage people to invent their own original questions.

See also - "Coin questions at the library" https://www.youtube.com/watch?v=M11WT3H_DqU suitable from kindergarten all the way up to high school.

#mtbos #edutwitter #riddles #informaleducation #mentalmath #puzzles

How to quickly calculate hypotenuse length C given right triangle side lengths A and B?

Calculate A+B, multiply by 5, and then divide by 7:

C≈5(A+B)/7

If the difference between A and B is less than 50%, your C will be off by 1% tops.

#mentalmath #mental #math #triangle #approximations