二、解决问题
★单元练习4
建议用时:6分钟
实际用时:分钟
6×2 =
81÷9 =
5×7 =
8÷2 =
3×9 =
30÷6 =
10÷3 =
20÷7 =
30÷4 =
40÷6 =
50÷8 =
63÷9 =
7×6 =
30÷5 =
3×5 =
700-400 =
470+200 =
350-200 =
700+500 =
85+60 =
20+47 =
320-50 =
50+60 =
60+390 =
760-80 =
77+80 =
400-90 =
260-70 =
34+61 =
60-6 =
76+18 =
180+40 =
560-400 =
30+610 =
280+50 =
30+170 =
560-90 =
70+250 =
860-400 =
200+650 =
90+520 =
80+360 =
410-90 =
600-30 =
70+209 =

6×2 = 12
81÷9 = 9
5×7 = 35
8÷2 = 4
3×9 = 27
30÷6 = 5
10÷3 = 3……1
20÷7 = 2……6
30÷4 = 7……2
40÷6 = 6……4
50÷8 = 6……2
63÷9 = 7
7×6 = 42
30÷5 = 6
3×5 = 15
700-400 = 300
470+200 = 670
350-200 = 150
700+500 = 1200
85+60 = 145
20+47 = 67
320-50 = 270
50+60 = 110
60+390 = 450
760-80 = 680
77+80 = 157
400-90 = 310
260-70 = 190
34+61 = 95
60-6 = 54
76+18 = 94
180+40 = 220
560-400 = 160
30+610 = 640
280+50 = 330
30+170 = 200
560-90 = 470
70+250 = 320
860-400 = 460
200+650 = 850
90+520 = 610
80+360 = 440
410-90 = 320
600-30 = 570
70+209 = 279

拓展园地
下图中共有多少个三角形？

5+4+3+2+1=15（个）
15×2=30（个）
答：图中共有30个三角形。