一、口算。
$27 + 15 =$ $82 ÷ 2 =$ $62 × 6 =$
$90 ÷ 6 =$ $96 - 28 =$ $75 ÷ 3 =$
$70 × 70 =$ $800 ÷ 4 =$ $220 - 80 =$
$204 ÷ 2 =$ $21 × 40 =$ $729 ÷ 9 =$
$390 + 30 =$ $109 × 3 =$ $70 × 12 =$
$288 ÷ 3 =$ $20 × 32 =$ $150 + 150 =$
$121 × 2 =$ $380 ÷ 2 =$ $23 × 50 =$
$154 ÷ 7 =$ $410 × 6 =$ $38 × 40 =$

一、42 41 372
15 68 25
4900 200 140
102 840 81
420 327 840
96 640 300
242 190 1150
22 2460 1520

二、用竖式计算，带*的要验算。
$18 × 25$         $64 × 32$ * $57 × 36$
$41 × 37$         $65 × 60$ * $48 × 25$

二、450 2048 2052
1517 3900 1200