《2025年心算口算巧算六年级上册北师大版》

1 计算下面各题。
1/6÷1/12 =
1/8÷5/8 =
2/3×1/3 =
7/24×20/21 =
15/16÷5/32 =
4/5×5/6 =
10/9×11/9 =
5/6×24 =
8/19÷1/4 =
9/20×7/9 =
1 5/8÷5/8 =
25/26×13/30 =
7/60×8 =
7/45×15/28 =
1 2/3×4/5 =
8/3÷4/3 =
1/3÷3/4 =
5/6÷1/4 =
7/12÷7/8 =
5/7÷7/5 =
3/5÷6/7 =

答案： 1/6÷1/12 = 1/6×12 = 2
1/8÷5/8 = 1/8×8/5 = 1/5
2/3×1/3 = 2/9
7/24×20/21 = 140/504 = 5/18
15/16÷5/32 = 15/16×32/5 = 6
4/5×5/6 = 20/30 = 2/3
10/9×11/9 = 110/81
5/6×24 = 20
8/19÷1/4 = 8/19×4 = 32/19
9/20×7/9 = 7/20
1 5/8÷5/8 = 13/8×8/5 = 13/5
25/26×13/30 = 325/780 = 5/12
7/60×8 = 56/60 = 14/15
7/45×15/28 = 105/1260 = 1/12
1 2/3×4/5 = 5/3×4/5 = 4/3
8/3÷4/3 = 8/3×3/4 = 2
1/3÷3/4 = 1/3×4/3 = 4/9
5/6÷1/4 = 5/6×4 = 10/3
7/12÷7/8 = 7/12×8/7 = 2/3
5/7÷7/5 = 5/7×5/7 = 25/49
3/5÷6/7 = 3/5×7/6 = 7/10

2 计算下面图形的周长与面积。
(1) r=2 cm
(2) 20 dm 40 dm

答案：
(1)周长=2×3.14×2=12.56cm，面积=3.14×2²=12.56cm²
(2)周长=2×40 + 3.14×20=80 + 62.8=142.8dm，面积=40×20 + 3.14×10²=800 + 314=1114dm²