12．口算：
0 158461 158469 158475 158479 158485 158487 158491 158497 158499 158505 158511 158515 158517 158521 158527 158529 158535 158539 158541 158545 158547 158551 158553 158555 158556 158557 158559 158560 158561 158563 158565 158569 158571 158575 158577 158581 158587 158589 158595 158599 158601 158605 158611 158617 158619 158625 158629 158631 158637 158641 158647 158655 199269
| 16×4= | 57×6= | 48÷8= | 96-69= |
| 41×5= | 3×70= | 60×70= | 47+35= |
| 45÷5= | 65+27= | 12×50= | 18×4= |
| 27÷3= | 53-35= | 38×3= | 61-39= |
| 15×8= | 25÷5= | 13×7= | 70×80= |