二、解决问题
★单元练习2
建议用时:6分钟
实际用时:分钟
350+30 =
62-10 =
65-56 =
900-600 =
700+600 =
24+56 =
42-23 =
87+9 =
36+40 =
34+26 =
605-237 =
453+284 =
680-290 =
470+207 =
231+379 =
78-9 =
76-30 =
36+7 =
370+70 =
800-200 =
100-20 =
960+600 =
720-80 =
97+100 =
60+160 =
278+205 =
78+346 =
375-189 =
377-347 =
127+35 =
430+70 =
600+5000 =
6400-4000 =
3100+200 =
360+600 =
1100-300 =
3600+400 =
1800-1000 =
1200-600 =
800+1200 =
83-59 =
69+350 =
408-211 =
528+394 =
763-586 =

350+30 = 380
62-10 = 52
65-56 = 9
900-600 = 300
700+600 = 1300
24+56 = 80
42-23 = 19
87+9 = 96
36+40 = 76
34+26 = 60
605-237 = 368
453+284 = 737
680-290 = 390
470+207 = 677
231+379 = 610
78-9 = 69
76-30 = 46
36+7 = 43
370+70 = 440
800-200 = 600
100-20 = 80
960+600 = 1560
720-80 = 640
97+100 = 197
60+160 = 220
278+205 = 483
78+346 = 424
375-189 = 186
377-347 = 30
127+35 = 162
430+70 = 500
600+5000 = 5600
6400-4000 = 2400
3100+200 = 3300
360+600 = 960
1100-300 = 800
3600+400 = 4000
1800-1000 = 800
1200-600 = 600
800+1200 = 2000
83-59 = 24
69+350 = 419
408-211 = 197
528+394 = 922
763-586 = 177

拓展园地
用3根火柴能摆一个三角形。如果要摆出6个相同大小的三角形，最少还需要增加几根火柴棒？

2×6 = 12（根）
12 - 3 = 9（根）
答：最少还需要增加9根火柴棒。