in reply to Re: My habitual errors
in thread My habitual errors

I always go "9 times x is i don't know, so x times 9 is"

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[OT] Re^3: My habitual errors
by Eimi Metamorphoumai (Deacon) on Apr 05, 2007 at 16:18 UTC
    Actually, 9 is easy. 9×d (where d is a single digit number) is always two digits, the first being d-1 and the second 10-d (or as I was taught, the second being enough so that the two add up to 9). So 9×3 is 27 (2 = 3-1, 2+7=9).