13.口算
60×90= | 500×80= | 600÷30= | 20×34= |
13×600= | 75-18= | 70-30= | 8000-300= |
120÷3= | 45×20= | 210×4= | 70×200= |
25×100= | 75÷3= | 125×8= | 300×40= |
12.哪道算式的积小于30000?( )
A. | 509×59 | B. | 509×61 | C. | 492×57 |
11.在乘法中,一个乘数乘10,另一个乘数乘20,得到的积就等于原来的积( )
0 160386 160394 160400 160404 160410 160412 160416 160422 160424 160430 160436 160440 160442 160446 160452 160454 160460 160464 160466 160470 160472 160476 160478 160480 160481 160482 160484 160485 160486 160488 160490 160494 160496 160500 160502 160506 160512 160514 160520 160524 160526 160530 160536 160542 160544 160550 160554 160556 160562 160566 160572 160580 199269
A. | 乘10 | B. | 乘20 | C. | 乘200 |