一、口算。
$68 + 25 =$ $7×40 =$ $500÷5 - 10 =$
$78÷3 =$ $19×3 =$ $76÷2÷2 =$
$66÷2 =$ $95÷5 =$ $9×(2 + 40) =$
$500 - 99 =$ $786×0 =$ $360÷3×6 =$
$500×6 =$ $905×5 =$ $880÷(15 - 7) =$
$380÷2 =$ $150×6 =$ $600 - 108×5 =$
$126÷7 =$ $808÷4 =$ $540÷9 + 120 =$
$312×2 =$ $624÷3 =$ $6×(60÷4) =$
$560÷5 =$ $180×3 =$ $102÷2÷3 =$
$112×5 =$ $244÷4 =$ $816÷(24÷3) =$

一、93 280 90
26 57 19
33 19 378
401 0 720
3000 4525 110
190 900 60
18 202 180
624 208 90
112 540 17
560 61 102

二、在括号里填合适的数。
$(\quad\quad) + 420 = 600$ $78 + (\quad\quad) = 100$ $(\quad\quad) - 105 = 95$
$120 - (\quad\quad) = 80$ $(\quad\quad) + 500 = 900$ $560 + (\quad\quad) = 880$
$(\quad\quad) - 520 = 410$ $620 - (\quad\quad) = 380$ $(\quad\quad) + 370 = 1000$
$364 + (\quad\quad) = 720$ $589 + (\quad\quad) = 705$ $940 - (\quad\quad) = 465$

二、180 22 200
40 400 320
930 240 630
356 116 475