【解答】解:7÷2=3(本)…1本.
3+1=4(本).
答:有一个抽屉至少要放4本.
故答案为:√.
三、计算题(本大题共2小题,满分26分.)
16.(16分)计算下面各题,能简便的要用简便方法.
(1)29×12+29×13+29×25+29×10
(2)9.75+99.75+999.75+9999.75
(3)
(4)(1+++)×(+++)﹣(1++++)×(++)
【解答】解:(1)29×12+29×13+29×25+29×10
=29×(12+13+25+10)
=29×60
=1740;
(2)9.75+99.75+999.75+9999.75
=9.75+99.75+999.75+9999.75+(0.25+0.25+0.25+0.25)﹣1
=(9.75+0.25)+(99.75+0.25)+(999.75+0.25)+(9999.75+0.25)﹣1
=10+100+1000+10000﹣1
=11110﹣1
=11109;
(3)
(4)
17.(10分)解方程
(1)5x+=2x+5
(2)﹣=3
【解答】解:(1)5x+=2x+5
5x+﹣2x=2x+5﹣2x
3x+=5
3x+﹣=5﹣
3x=5
3x÷3=5÷3
x=;
(2)﹣=3
×0.05﹣×0.05=3×0.05
0.25(x﹣2)﹣0.2(x﹣1)=0.15
0.05x﹣0.3=0.15
0.05x﹣0.3+0.3=0.15+0.3
0.05x=0.45
0.05x÷0.05=0.45÷0.05
x=9.