圆:面积为4,
则半径平方为:4÷3.14≈1,
即半径约等于1,
周长为:3.14×2×1=6.28,
因为8>6.28,
所以正方形的周长大于圆的周长,
故答案为:√.
四、细心计算.(共分)
31.(5.00分)直接写出得数.
496﹣298=7.25+=1.4÷0.7=4.37+6.63=35﹣1.4=
6.8÷17=90%×=1÷75%=(+)×12=55÷=
【解答】解:
496﹣298=1987.25+=81.4÷0.7=24.37+6.63=1135﹣1.4=33.6
6.8÷17=0.490%×=22.5%1÷75%=(+)×12=1455÷=50
32.(6.00分)简便运算.
(﹣)×15 4×0.8×2.5×12.5 57×99+57
9.6﹣1.46﹣0.54 897÷25÷4 5.8×4.7+4.2×4.7.
【解答】解:(1)(﹣)×15
=×15﹣×15
=10﹣3
=7;
(2)4×0.8×2.5×12.5
=(4×2.5)×(0.8×12.5)
=10×10
=100;
(3)57×99+57
=57×(99+1)
=57×100
=5700;
(4)9.6﹣1.46﹣0.54
=9.6﹣(1.46+0.54)
=9.6﹣2
=7.6;
(5)897÷25÷4
=897÷(25×4)
=897÷100
=8.97;
(6)5.8×4.7+4.2×4.7
=(5.8+4.2)×4.7
=10×4.7