1.88888888x88888888分之1+2+3+4+5+6+7+8+7+6+5+4+3+2+1
=88888888x88888888分之8x8
=11111111x11111111
2.(1234+4567×7890)÷(4568×7890-6656)
=(1234+4567×7890)÷(4568×7890-7890+1234)
=(1234+4567×7890)÷(4567×7890+1234)
=1
3.121121121121/212121212121
=(121*1001001001)/(21*10101010101)
=121*12
=1452
4.1001-1/2001-2/2001-3/2001-……2001/2001
=1001-(1/2001+2/2001+3/2001+……+2001/2001)
=1001-[1/2001×(1+2+3+……+2001)]
=1001-[1/2001×(1+2001)×2001÷2]
=1001-[(1+2001)÷2]
=1001-1001
=0