Any math geeks here?



  • Does anyone know why regardless of what integer number you multiply by 9, the sum of the digits of the result is always 9?

    149=126 1+2+6=9
    52
    9=468 4+6=10 1+0=1 1+8=9
    879=783 7+8=15 1+5=6 6+3=9
    56324
    9=506916 5+6=11 1+1=2 2+9=11 1+1=2 2+1+6=9



  • 1 x 9 = 09 -> 0 + 9
    2 x 9 = 18 -> 1 + 8
    3 x 9 = 27 -> 2 + 7
    4 x 9 = 36 -> 3 + 6
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    with each multiplication, the right digit decreases by 1 and the left digit increase by 1 so the sum of the digits will always remains the same, 9. A similar pattern may also apply to higher digit numbers. I'am not a math geek and this may not be the correct reason, but thinking about it, I just got this pattern.


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