有規律的算式

 

9 = 81+1

98 = (81+1)10+8 = 80+10+8 = 8(10+2)+2 = 812+2

987 = ( 812+2)10+7 = 8120+20+7 = 8(120+3)+3 = 8123+3

9876 = (  8123+3)10+6 = 81230+30+6 = 8(1230+4)+4 = 81234+4

只需善用運算的結合律與分配律就可獲得上述算式

依此類推可得下列算式

987654321 = 8 123456789 + 9
98765432 = 8 12345678 + 8
9876543 = 8 1234567 + 7
987654 = 8 123456 + 6
98765 = 8 12345 + 5
9876 = 8 1234 + 4
987 = 8 123 + 3
98 = 8 12 + 2
9 = 8 1 + 1

 

 


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