（1+3+5+…+1997）-（2+4+6+…+1994+1996）=______．
1+3+5+…+1997共有加數(shù)：
÷2+1=999個；
2+4+6+…+1994+1996共有加數(shù)：
÷2+1=998個；
所以：
（1+3+5+…+1997）-（2+4+6+…+1994+1996）
=（1997+1）×999÷2-（1996+2）×998÷2，
=1998×999÷2-1998×998÷2，
=（999-998）×1998÷2，
=1×999，
=999．
故答案為：999．
練習冊系列答案
相關(guān)習題

科目：小學數(shù)學 來源： 題型：

0.56÷0.04= 1.44÷2= 24.6÷0.6= 4.5÷0.15=
0.63÷0.09= 12.84÷1.2= 3.9÷0.13= 1.6÷1.6=
20÷0.25= 1.3÷2.5= 100÷12.5= 7.8÷0.13=
3.24÷0.8= 13×1.1= 5.46÷3= 4.07×3=
5.28t-1.99t= 0.6+89= 5.7×0.1= 1.6÷0.4=
6÷0.3= 5÷0.25= 0.45×3= 0.35×8=
7.1-0.76= 1.2×0.3= 0.76÷4= 1.9×0.8=
4.2-2.8= 7.2÷1.6= 19.8+3.2= 18-17.45=
4.5+1.5= 0.75x+0.25x= 2.5×4= 0.46÷2=
0.7×1.4= 1-0.92= 8×0.125= 3.4÷20=
10a-1.8a= 4.8×0.2= 0.3÷0.15= 0.15÷2=
0.2×0.5= 2.2-1.8= 3.1+1.75= 32.8+1.9=
0.42×0.5= 0.76+1.24= 3.06-0.72= 0.51÷17=
5.2÷13= 8.2×0.01= 1.72-0.73= 1.6×0.4=
4.8b+3.2b= 2.5×4= 0.3×101= 1.2×0.5=

查看答案和解析>>

科目：小學數(shù)學 來源： 題型：

180÷60= 12×25= 0÷90=
4×5÷4×5= 0.25×4+4= 131+218+269+182=
25×6×4= 420÷35= 36×5×4=
120÷5÷3= 198-75-25= 120-20÷5=
59億-58億= （1.3+3.5）÷0.6= 75÷2.5=
0.45÷1.25÷8= 2.5×7.6×4= 97.6÷0.02=
8.8-（0.25+0.4）= 0.25+87+0.75= 0.8-0.35×2=
0.1÷0.01×0.1= 9.9+9.9×99= 2.7×3.6+6.4×2.7=
720÷8÷9= 2.9+5.7+2.1= 2-0.16-0.64=
16.7+84.5-16.7= 6.8-（3.8+2.9）= 9×1.3+9×6.7=
5.5-5.25+5.2= 0.8×25-10= 42.8×25×4=
7.2+2.8= 0.9÷0.01= 3.5+7.6=
3×0.2×0.5= 0.96÷0.3= 1.5×0.4=
7÷0.25= 2.5×0.7×0.8= 8-2.5=
16÷1.6= 5.6×1.01= 8×（2.5+0.25）=
0.36+0.64= 64.32÷16= 72.8÷0.8=
8.4×0.2+1.6×0.2= 8.4÷4.2= 0.05×0.8=
2.56-0.37= 1.23×3= 25×0.8×0.5=
12×2.5= 3.2÷1.6= 3.5+3.5×3=
19.6÷2= 8.8÷2.2= 3.9+2.03=
7.2×0.3+2.8×0.3= 13.8+9.9= 2.4×2.5=
0.75×4= （1.5+0.25）×4= 4.2÷0.1=
4.2÷3.5= 2.14-0.9= 27+456+73=
12÷0.3= 2.87÷0.7= 13÷4=
24÷4+56÷4= 2.1×0.3÷2.1= 2.3-0÷8.1=
1.37-1.37÷1.37= 4.4÷（5×0.2）= 7×1.3=
0.96÷0.06= 0.36×0.3= 0.35÷0.7=
13.65÷13= 4×0.8×0.25×1.25= 13+0.7÷0.7=
7.05×23.7+7.05×76.3= 0.125×3.2×2.5= （12+23.1÷0.75）×0.4-5.12=
728+199= 637-201= 16×25=
1.6×[（12-7.2）÷（0.84÷2.1）]=

查看答案和解析>>

科目：小學數(shù)學 來源： 題型：

（2007?西藏）求未知數(shù)x
（1）3x+4.5=9
1
2
 （2）50%x-1.3×5=1.25 （3）8×（0.4x+2）=24．

查看答案和解析>>

科目：小學數(shù)學 來源： 題型：解答題

180÷60=12×25=0÷90=
4×5÷4×5=0.25×4+4=131+218+269+182=
25×6×4=420÷35=36×5×4=
120÷5÷3=198-75-25=120-20÷5=
59億-58億=（1.3+3.5）÷0.6=75÷2.5=
0.45÷1.25÷8=2.5×7.6×4=97.6÷0.02=
8.8-（0.25+0.4）=0.25+87+0.75=0.8-0.35×2=
0.1÷0.01×0.1=9.9+9.9×99=2.7×3.6+6.4×2.7=
720÷8÷9=2.9+5.7+2.1=2-0.16-0.64=
16.7+84.5-16.7=6.8-（3.8+2.9）=9×1.3+9×6.7=
5.5-5.25+5.2=0.8×25-10=42.8×25×4=
7.2+2.8=0.9÷0.01=3.5+7.6=
3×0.2×0.5=0.96÷0.3=1.5×0.4=
7÷0.25=2.5×0.7×0.8=8-2.5=
16÷1.6=5.6×1.01=8×（2.5+0.25）=
0.36+0.64=64.32÷16=72.8÷0.8=
8.4×0.2+1.6×0.2=8.4÷4.2=0.05×0.8=
2.56-0.37=1.23×3=25×0.8×0.5=
12×2.5=3.2÷1.6=3.5+3.5×3=
19.6÷2=8.8÷2.2=3.9+2.03=
7.2×0.3+2.8×0.3=13.8+9.9=2.4×2.5=
0.75×4=（1.5+0.25）×4=4.2÷0.1=
4.2÷3.5=2.14-0.9=27+456+73=
12÷0.3=2.87÷0.7=13÷4=
24÷4+56÷4=2.1×0.3÷2.1=2.3-0÷8.1=
1.37-1.37÷1.37=4.4÷（5×0.2）=7×1.3=
0.96÷0.06=0.36×0.3=0.35÷0.7=
13.65÷13=4×0.8×0.25×1.25=13+0.7÷0.7=
7.05×23.7+7.05×76.3=0.125×3.2×2.5=（12+23.1÷0.75）×0.4-5.12=
728+199=637-201=16×25=
1.6×[（12-7.2）÷（0.84÷2.1）]=

查看答案和解析>>

科目：小學數(shù)學 來源： 題型：解答題

0.56÷0.04=1.44÷2=24.6÷0.6=4.5÷0.15=
0.63÷0.09=12.84÷1.2=3.9÷0.13=1.6÷1.6=
20÷0.25=1.3÷2.5=100÷12.5=7.8÷0.13=
3.24÷0.8=13×1.1=5.46÷3=4.07×3=
5.28t-1.99t=0.6+89=5.7×0.1=1.6÷0.4=
6÷0.3=5÷0.25=0.45×3=0.35×8=
7.1-0.76=1.2×0.3=0.76÷4=1.9×0.8=
4.2-2.8=7.2÷1.6=19.8+3.2=18-17.45=
4.5+1.5=0.75x+0.25x=2.5×4=0.46÷2=
0.7×1.4=1-0.92=8×0.125=3.4÷20=
10a-1.8a=4.8×0.2=0.3÷0.15=0.15÷2=
0.2×0.5=2.2-1.8=3.1+1.75=32.8+1.9=
0.42×0.5=0.76+1.24=3.06-0.72=0.51÷17=
5.2÷13=8.2×0.01=1.72-0.73=1.6×0.4=
4.8b+3.2b=2.5×4=0.3×101=1.2×0.5=

查看答案和解析>>

同步練習冊答案