一、口算。
$61 - 16 =$
$84 ÷ 2 =$
$3 × 42 =$
$34 × 2 =$
$47 + 38 =$
$56 ÷ 2 =$
$85 ÷ 5 =$
$32 × 8 =$
$14 × 7 =$
$760 - 580 =$
$420 ÷ 6 =$
$990 ÷ 9 =$
$103 × 5 =$
$170 × 4 =$
$404 × 9 =$
$848 ÷ 4 =$
$121 + 278 =$
$630 ÷ 6 =$
$256 ÷ 2 =$
$206 × 3 =$
$565 ÷ 5 =$
$122 × 4 =$
$832 ÷ 2 =$
$125 × 2 =$

一、45 42 126
68 85 28
17 256 98
180 70 110
515 680 3636
212 399 105
128 618 113

二、计算下面各题。
$844 ÷ 4 + 160$
$314 × 3 ÷ 2$
$280 × 2 + 377$
$3 × (915 ÷ 5)$
$(346 - 185) × 8$
$462 ÷ (18 ÷ 6)$

二、371 471 937
549 1288 154