作业帮5行8列40个正方组成多少长方形?
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5行8列40个正方组成多少长方形?
5行8列40个正方组成多少长方形?
5行8列40个正方组成多少长方形?
1x2 :7x5 = 35
1x3 :6x5 = 30
1x4 :5x5 = 25
1x5 :4x5 = 20
1x6 :3x5 = 15
1x7 :2x5 = 10
1x8 :1x5 = 05
---------------------------
Subtotal = 140
2x1 :4x8 = 32
2x3 :4x6 = 24
2x4 :4x5 = 20
2x5 :4x4 = 16
2x6 :4x3 = 12
2x7 :4x2 = 08
2x8 :4x1 = 04
---------------------------
Subtotal = 116
3x1 :3x8 = 24
3x2 :3x7 = 21
3x4 :3x5 = 15
3x5 :3x4 = 12
3x6 :3x3 = 09
3x7 :3x2 = 06
3x8 :3x1 = 03
---------------------------
Subtotal = 90
4x1 :2x8 = 16
4x2 :2x7 = 14
4x3 :2x6 = 12
4x5 :2x4 = 08
4x6 :2x3 = 06
4x7 :2x2 = 04
4x8 :2x1 = 02
---------------------------
Subtotal = 62
5x1 :1x8 = 8
5x2 :1x7 = 7
5x3 :1x6 = 6
5x4 :1x5 = 5
5x6 :1x3 = 3
5x7 :1x2 = 2
5x8 :1x1 = 1
---------------------------
Subtotal = 32
Grand total = 140 + 116 + 90 + 62 + 32 = 440
(8+7+6+5+4+3+2+1)*(5+4+3+2+1)=36*15=540个