口算．（近似值符号的是估算题）
0.105×100= 1993+1994= 603×39≈ 4950÷51= 112﹣102=
16×0.25= 19÷9﹣10÷9= 
﹣
= 8π≈ 2.63+3.7=
1﹣+
= 7×8×（
+
）= 1﹣
÷= 
÷
×0=
口算．（近似值符号的是估算题）
0.105×100= 1993+1994= 603×39≈ 4950÷51= 112﹣102=
16×0.25= 19÷9﹣10÷9= ﹣= 8π≈ 2.63+3.7=
1﹣+= 7×8×（+）= 1﹣÷= ÷×0=
= 24×
=
×
÷
=
÷
=
×
÷
×
=
，文艺书相当于全部书的
，其中科技书有250本，阅览室里共有多少本书？
= 4
= 6﹣1
= 4
= 1
=
=
= 5
=
=
= 4.5﹣
=
=
=
÷10=
×
×
=
×
=
÷
= 6×
=
×9×
= 5÷
÷5=
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