观察：3.53=3.5×5+3×3，33.5=3×5+3.5×3,那么：（1）mn=( )；（2）若x(2.46)=210，那么x=？
直接写得数 ×=÷=×=÷= 4÷=×6÷= 6×+6×=（+）×16=×= 24%×5=
口算小博士．×=÷2= 80%﹣20%= 4×25%+16×25%=×=×72%=×÷=×÷×=
直接写得数．×= 1÷= 4×60%= 0.875÷0.125= 0.25××4=÷2= 10÷=×3.6=（）2=÷×0=
口算：×= 45×=÷10= 0÷8= 5.4×=÷= 0.65×= 50%﹣0.05=
直接写出得数 1÷= 1﹣=÷= 48×12.5%=+=×=÷10= 5÷﹣÷5=
3=3.5×5+3×3，3
×
=
÷
=
×
=
÷
= 4÷
=
×6÷
+6×
=（
+
）×16=
×
= 24%×5=
×
=
÷2= 80%﹣20%= 4×25%+16×25%=
=
×72%=
×
÷
=
×
÷
×
= 1÷
= 4×60%= 0.875÷0.125= 0.25×
×4=
÷2= 10÷
=
×3.6=（
）2=
÷
×0=
×
= 45×
=
÷10= 0÷8
=
=
÷
= 0.65×
= 50%﹣0.05=
= 1﹣
=
= 48×12.5%=
+
=
×
=
÷10= 5÷
﹣
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