原式=(1+17)X17/2+18X5684
=18X17/2+18X5684
=9X17+9X2x5684
=9X(17十2x5684)
=9×11385
=102465
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1+2+3+4+5+6+7+8+9+10+11+12+13+
14+15+16+17+18*5684
=(1+17)+(2+16)+(3+15)+(4+14)
+(5+13)+(6+12)+(7+11)+(8+10)
+9+18*5684
=8*18+18*5684+9
=(8+5684)*18+9
=5692*18+9
=102456+9
=102465
=(1+17)*17/2+18*5684
=18*(5684+17/2)
=18*(5684+8+1/2)
=(2*9)*5692+9
=(2*(10-1)))*5692*(10-1)
=(10-1)(5692*2+1)
=113850-11385
=102465