6.在$\frac{11}{9}$、$\frac{13}{25}$、$\frac{3}{16}$、$\frac{7}{28}$、$\frac{13}{39}$中,不能化成有限小数的分数有( )个.
A. | 2 | B. | 3 | C. | 4 |
18.用你喜欢的方法计算
0 157545 157553 157559 157563 157569 157571 157575 157581 157583 157589 157595 157599 157601 157605 157611 157613 157619 157623 157625 157629 157631 157635 157637 157639 157640 157641 157643 157644 157645 157647 157649 157653 157655 157659 157661 157665 157671 157673 157679 157683 157685 157689 157695 157701 157703 157709 157713 157715 157721 157725 157731 157739 199269
(1-$\frac{1}{2}$-$\frac{1}{4}$)÷$\frac{1}{4}$ | $\frac{3}{8}$×$\frac{5}{6}$×2$\frac{2}{3}$ | $\frac{9}{17}$÷9+$\frac{1}{9}$×$\frac{8}{17}$ |
6÷20%-9 | $\frac{1}{14}$×$\frac{1}{3}$+$\frac{1}{14}$×$\frac{2}{3}$ | ($\frac{1}{2}$-$\frac{3}{8}$)÷$\frac{3}{4}$ |