Hey folks, I do appreciate the increased readership and renewed interest in MathNotations. I'm definitely a "binge" blogger, prolific for a few weeks, then burning out like a SuperNova, 'retweeting' into oblivion again. I miss doing video solutions of some problems but I don't know if that will happen. Since I get lots of views but zero comments, I really don't know if I should continue...
EXPLAIN USING MENTAL MATH IN 10 SEC OR LESS...
72÷25=2.88
72 × 25 = 1800
Just curiosities to grab students and then fade away OR do you see these as worthwhile for developing deeper understanding of number operations?
For example, dividing by 25 is equivalent to multiplying by 4, then ÷ by 100.
How would you develop or extend this investigation?
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Saturday, January 26, 2013
MENTAL MATH TRICKS OR SOMETHING DEEPER
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2 comments:
I definitely think this kind of trick is useful (though perhaps not necessary). For example, when dividing big numbers by 5, I find it a lot faster to multiply by 2 then divide by 10. Anyone else do this?
Yes, I do that too. Considering the weaknesses we see in students', I think getting them to understand WHY div by 5 is equiv to mult by 2 and div by 10 is definitely worthwhile!
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