Multiply in your head, the teens

The red area is 200
The blue area is the product of the final digits.
So, for example, 13 * 17 = 200 + 21
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The same picture can be drawn for multiplication of certain two 2-digit numbers in the 20's, the 30's, etc, where the basic "red" amount is the product of the upper and the lower multiple of ten. 32*38=30*40+2*8, for example; or 1216
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If you can multiple the numbers from 1 through 19 in your head, which is not all that hard, you can then extend this same method to multiplying two numbers in adjacent "tens", where the units add to 10
like 21*39 = 20*40+1*19 = 800 + 19 = 819, and
like 23*37 = 20*40+3*17 = 800 + 51 = 851, and
like 30*30 = 20*40+10*10= 800 +100 = 900

March On Washington

August 28, 1963 I HAVE A DREAM

That someday soon we will be allowed to do this again.
36 CFR 7.96(g)(3)(ii)(B)
The Lincoln Memorial, ... and the single series of marble stairs immediately adjacent to and below that level.
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Oops. Turns out we can. My bad.

The role of ideas

John Conyors reacts to Keith Hayden's lies