(21)98989898×99999999÷1010101÷11111111
(22)4.8×(11.03-15.6÷7.5)
(23)(67.8+9.48) ÷0.96-2.58×30.05
(24)[1.7+1.7×(5.8-2.8)]+(1.75÷1.4)
(25)3.04×8.7-3.04×2.9+5.8×6.96
(26)(0.1+0.2+0.3+0.4+…+1)÷5.5
(27)3.14×6.5+4.5×3.14-3.14
(28)1240×3.8+124×51+1.24×1400+760×9.6+0.76×700
(29)1÷(2÷3) ÷(3÷4) ÷(4÷5) ÷…÷(1999÷2000)
(30)1-2+3-4+5-6+…-98+99-100+100