7 x 7 = 49
6 x 8 = 48
5 x 5 = 25
4 x 6 = 24
10 x 10 = 100
9 x 11 = 99
One of my 3rd Graders pointed this out while we were looking at the multiplication table. Great!
Challenge: make a diagram that explains this to a 3rd Grade class.
What I did is below... (1/2)
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I have a 6 giving itself away to as many of its comrades as it can.
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@mpershan
Nice visual investigation of this (similar to those shared here) in Mindset Mathematics Grade 3
@joboaler
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@mpershan
I did these in my head in the time it took to read them. Was there something I missed? Of value that is.
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@stampingout
Of value? I have no idea what you consider of value but there is an interesting mathematical pattern here. In algebra we'd express it as (n + 1)(n - 1) = n^2 - 1.
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@mpershan
Lots more to this story. E.g.,
3x1 = 3
1x2 = 2
5x2= 10
3x3 = 9
7x3 = 21
5x4 = 20
9x4 = 36
7x5 = 35
It's the tip of an iceberg. Challenge: expose the iceberg.
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