=4.5×0.2，
=0.9；
（2）90.7×99+90.7，
=90.7×（99+1），
=90.7×100，
=9070；
（3）
| 9 |
| 20 |
| 1 |
| 2 |
| 2 |
| 5 |
| 4 |
| 5 |
=
| 9 |
| 20 |
| 1 |
| 2 |
| 6 |
| 5 |
=
| 9 |
| 20 |
| 3 |
| 5 |
=
| 9 |
| 20 |
| 5 |
| 3 |
=
| 3 |
| 4 |
（4）
| 13 |
| 18 |
| 5 |
| 6 |
| 2 |
| 3 |
| 3 |
| 8 |
=
| 13 |
| 18 |
| 5 |
| 6 |
| 1 |
| 4 |
=
| 13 |
| 18 |
| 13 |
| 12 |
=
| 13 |
| 18 |
| 12 |
| 13 |
=
| 2 |
| 3 |
| 9 |
| 20 |
| 1 |
| 2 |
| 2 |
| 5 |
| 4 |
| 5 |
| 13 |
| 18 |
| 5 |
| 6 |
| 2 |
| 3 |
| 3 |
| 8 |
| 9 |
| 20 |
| 1 |
| 2 |
| 2 |
| 5 |
| 4 |
| 5 |
| 9 |
| 20 |
| 1 |
| 2 |
| 6 |
| 5 |
| 9 |
| 20 |
| 3 |
| 5 |
| 9 |
| 20 |
| 5 |
| 3 |
| 3 |
| 4 |
| 13 |
| 18 |
| 5 |
| 6 |
| 2 |
| 3 |
| 3 |
| 8 |
| 13 |
| 18 |
| 5 |
| 6 |
| 1 |
| 4 |
| 13 |
| 18 |
| 13 |
| 12 |
| 13 |
| 18 |
| 12 |
| 13 |
| 2 |
| 3 |