1. 直接写出得数。
$83 - 28 =$ $40 + 700 =$ $180 + 400 =$ $75 - 57 + 21 =$
$77 ÷ 7 =$ $800 + 2000 =$ $1260 - 760 =$ $64 + 17 - 21 =$
$25 + 49 =$ $400 - 90 =$ $580 - 500 =$ $94 - 28 - 12 =$
$90 - 52 =$ $3800 - 300 =$ $350 + 600 =$ $84 - 39 - 20 =$
$10 × 6 =$ $1400 - 600 =$ $1500 - 300 =$ $86 - 48 + 30 =$
$70 - 23 =$ $2700 - 800 =$ $600 + 350 =$ $56 + 29 - 12 =$
$2100 - 400 =$ $900 + 700 =$ $990 + 10 =$ $5700 - 700 - 800 =$
$900 + 500 =$ $4000 + 5000 =$ $880 + 40 =$ $1200 + 1200 + 1300 =$

1. 55 740 580 39 11 2800 500 60 74 310 80 54 38 3500 950 25 60 800 1200 68 47 1900 950 73 1700 1600 1000 4200

2. 用竖式计算，带 * 的要验算。
$903 - 634 =$ $196 + 487 =$ * $500 - 136 =$
$764 + 486 =$ $620 - 328 =$ * $872 + 432 =$

2. 1400 9000 920 3700 269 683 364 1250 292 1304 竖式及验算略

(1)$◯ 4△ + 2\mathrm{☆}6 = 704$ (2)$□ 3△ - \mathrm{☆}2 = 57$
$◯ =$() $□ =$()
$△ =$() $△ =$()
$\mathrm{☆} =$() $\mathrm{☆} =$()

·思维提升
（1）4 8 5
（2）1 9 8