Multiplying Numbers Just Under 100 [Math Trick Monday] #mathtrickmonday #mentalmath #numbersense

Multiplying two two-digit numbers just under 100 can be computed much more simply with two subtractions and a single digit multiplication.

This is a great trick if you participate in UIL Number Sense or are looking for other fast mental math techniques. Follow for more number sense tips.

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[ashishd]

Why this works is (x-a)*(x-b)=x^2-(a+b)*x+a*b =x(x-(a+b))+a*b
.. .put x=100

[Stitchalatte]

I learn something new every time I watch your videos!

[msa]

thank you very much for sharing your math tips for free

[flavrt]

It works. I hate these specialized algorithms because we never get the proofs or limits.

[lucky]

Interesting, never learned anything like this!

[igtheories]

How far should it be from hundred to work

[shanti]

Very nice! Thanks for fast math tricks! Thanks to awesome age old Vedic Math's originated from India!

[bendows]

Why don’t we learn a bunch of these in school? Especially for non-calculator tests

[raymondvogtner]

You subtracted 3 from 92, but in the next one you subtract the first number from the second. Why?

[Lilobababoi]

Nice trick for positif number 100 and 10 - 8 = 2 😅 that trick not be able for 10 number its just 1 to 9 idk but just view minutes imagine

[pete]

It's fine so long as you don't go below 90 x 91. Try this method with, say, 45 x 73. Or 84 x 89. Then you're in the "twilight zone", lol.