1. 直接写出得数。
64 + 36 = 39 + 9 = 77 - 30 = 75 + 14 + 40 =
9 + 17 = 11 + 79 = 43 - 34 = 46 - 23 + 60 =
20 + 29 = 80 + 60 = 80 - 28 = 60 + 12 - 18 =
46 + 34 = 51 - 36 = 400 + 700 = 18 + 80 + 50 =
95 - 37 = 87 - 59 = 1700 - 600 = 6700 - 700 + 600 =
73 - 56 = 90 - 79 = 600 + 900 = 800 + 700 + 600 =
780 - 80 = 47 + 35 = 6800 - 6000 = 1800 - 600 - 200 =

1. 100 48 47 129
26 90 9 83
49 140 52 54
80 15 1100 148
58 28 1100 6600
17 11 1500 2100
700 82 800 1000

2. 用竖式计算，带 * 的要验算。
154 + 268 = * 902 - 635 = 523 + 283 - 327 =
716 + 384 = * 504 + 596 = 910 - 190 - 77 =

2. 422 267 479
1100 1100 643
竖式及验算略

3. 先选出错因(填序号)，再改正。
① 百位上忘记减被借走的 1 ② 相同数位没有对齐
③ 隔位退位时，十位上忘记减被借走的 1

3. ②$\begin{array}{r} 315\\ -23\\ \hline 292\end{array} $

①$\begin{array}{r} 348\\ -194\\ \hline 154\end{array} $

③$\begin{array}{r} 603\\ -268\\ \hline 335\end{array} $