re: Can you do multiplication in your head thru 12?

quote:

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9 x 3
9 x 4
9 x 6
9 x 7
9 x 8
9 x 12
Damn I need to work on my 9's.

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9's are easy. Remember the answer will add up to nine, or is divisible by 9, such as,
9x4=36; 3+6=9
9x5=45; 4+5=9
9x6=54; 5+4=9
9x7=63; 6+3=9
9x8=72; 7+2=9
9x10=90; 9+0=9
9x11=99; 9+9=18; 1+8=9 or 18/9=2
9x12=108; 1+0+8=9
9x13=117 1+1+7=9
9x14=126 1+2+6=9
9x15=135; 1+3+5=9
9x16=144
9x17=153
9x18=162
9x19=171
9x20=180
9x21=189; 1+8+9=18 which is divisible by 9; 18/9=2