一间教室用边长0.4米的正方形砖铺地，需要300块，如果改用边长0.5米的正方形砖铺地，需要多少块？
直接写结果﹣= 570÷ ×20= +3.5=11﹣﹣= ×= 1÷= 10﹣=÷= 19.9+19.9×99=
直接写出得数．﹣= 12×= ÷26= +=×= += 1÷= ×=
口算﹣= += ×= ÷7=
直接写出得数．（1）1﹣0.25=（2）+=（3）2﹣=（4）0.5×=（5）20%÷=（6）×30%=（7）×=（8）0÷=
直接写出得数：÷= ÷3= ××= ×9×=÷2= 5÷﹣÷5= 2.7﹣= 6×=（1.6+3.2）×0.125= 1÷= ÷10= 6×=1﹣75%= ÷= ×= 5÷1%=4÷=
﹣
= 570÷
×20= 
﹣
= 
×
= 1÷
= 10﹣
=
÷
= 19.9+19.9×99=
﹣
= 12×
= 
÷26= 
+
=
×
= 
+
= 1÷
= 
×
=
﹣
= 
+
= 
×
= 
÷7=
+
=
=（4）0.5×
=
×30%=
×
=（8）0÷
=
÷
= 
÷3= 
×
×
= 
×9×
÷2= 5÷
﹣
= 6×
=
= 
÷10= 6×
=
÷
= 
×
= 5÷1%=
=
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