27+2.2+1.42-0.8-(2.52+1.3)×1000

1. 27+2.2+1.42-0.8-(2.52+1.3)×1000

（1）2.2+1.42-0.8=2.82元．
  答：星期三收盘时，该股票涨了2.82元．
  （2）27+2.2+1.42=30.62元．
  27+2.2+1.42-0.8-2.52=27.30元．
  答：本周内该股票的最高价是每股30.62元；最低价是每股27.30元．
  （3）27+2.2+1.42-0.8-2.52+1.3=28.6元，
  28.6×1000×（1-1.5‰-1‰）-27×1000×（1+1.5‰）=28528.5-27040.5=1488元．
  答：小杨在星期五收盘前将全部股票卖出，则他将赚1488元．

2. 2.78-0.46+2.22-0.54

2.78-0.46+2.22-0.54
=2.78+2.22-（0.46+0.54）
=5-1
=4

3. 2.56/0.04/0.5 1.92*0.12-2.7

图

4. 2.01+2.02+2.03+2.04+……+2.49+2.5

首末向中间以两个数一组，共分25个数值相等的组
=2.01+2.50+2.02+2.49+.......+2.25+2.56
=4.51*25
=112.75

5. 1.8*41+2.2*25%=？

1.8*41+2.2*0.25=73.8+0.55=74.35

6. 2.8*4+7.2/0.25

如图：2.8*4+7.2/0.25=40

7. 2.73×69+69×9.9+27.3×3.1

2.73×69+69×9.9+27.3×3.1
=2.73x69+2.73x31+69x（10-0.1）
=2.73x（69+31）+69x10-69x0.1
=2.73x100+690-6.9
=273+690-6.9
=963-6.9
=956.1

8. 27.5×1.4+0.96×275-2.75×10

=275×（0.14+0.96－0.1）
=275×1
=275