求小学四年级下数学小数简便递等式

求小学四年级下数学小数简便递等式
求小学四年级下数学小数简便递等式

求小学四年级下数学小数简便递等式
简便运算
1.1-2+3-4+5-6+7-8+9-10+11-12+.+2003-2004+2005-2006+2007
=1+（3-2）+（5-4）+.+（2007-2006）
=1+（2007-1）/2
=1005
2、480+325+75
=480+(325+75)
=480+400
=880
3、295-128-72
=295+（128+72）
=295+200
=495
4、43×25×4
=43×（25×4）
=43×100
=4300
5、102×43
=（100+2）×43
=100×43+2×43
=4300+86
=4386
6、9×37+9×63
=9×（63+37）
=9×100
=900
7.66×38-987÷21 66×38-987÷21
=2508-987÷21 =2508-47
=2508-47 =2461
=2461
8.1.25*17.6+36.1/0.8+2.36*12.5
1.25*17.6+36.1/0.8+2.36*12.5
=(5/4)*17.6+36.1*(5/4)+23.6*(50/4)
=176/8+361/8+236/8
=773/8=96.625
9.7.5*2.3+1.9*2.5
7.5*2.3+1.9*2.5
=7.5*(1.9+0.4)+1.9*2.5
=(7.5+2.5)*1.9+7.5*0.4
=19+3 =22
10.2004/2003*2005
2004/2003*2005
=(2004/2003)*(2003+2)
=2004+4008/2003
11.276*543-267/276+543*275
276*543-267/276+543*275
=543*(276+275)-267/276
=543*551-267/276
12.2002+2001-2000-1999+1998+1997-1996-1995+……+2+1
=(2002-2000)+(2001-1999)+(1998-1996)+(1997-1995)+……+(6-4)+(5-3)+2+1
=2+2+2+2+……+2+2(从3-2002共2000个数,所以有1000个2)+2+1
=1000×2+2+1
=2003
13.1/3+1/15++1/35+1/63+九十1/9
=1/(1×3)+1/(3×5)+1/(5×7)+1/(7×9)+1/(9×11)
=1/2×(1-1/3)+1/2×(1/3-1/5)+1/2×(1/5-1/7)+1/2×(1/7-1/9)+1/2×(1/9-1/11)
=1/2×(1 - 1/3 + 1/3 - 1/5 + 1/5 - 1/7 + 1/7 - 1/9 + 1/9 - 1/11)
=1/2×(1-1/11)
=1/2×10/11
=5/11
14.0.49÷1.4 1.25×2.5×32 3.6－0.6×2
15.3.65×10.1 3.6－3.6×0.8 15.2÷0.25÷4
16.5.6÷3.5 9.6÷0.8÷0.4 4.2×99＋4.2
17.0.89×100.1 146.5－(23＋46.5) 17.8÷(1.78×4)
18.5.83×2＋4.27 (45.9－32.7)÷8÷0.125 9.7×99＋9.7
19.4.36×12.5×8 15.6×13.1－15.6－15.6×2.1 0.65×101
20.27.5×3.7－7.5×3.7 8.54÷2.5÷0.4 3.83×4.56＋3.83×5.44
21.9.9×0.625×101－62.5
22.9.9×8.6＋0.86
23.0.46×7.5＋0.46×2.5
24.4.6×8.04＋6.4×8.04－8.04
25.5.4×0.15÷0.2+4.6×0.15
=27*0.15+4.6*0.15
=(27+4.6)*0.15
=31.6*0.15
=4.74
26.55×10.43+104.3×4.4+104.3×0.1
=55×10.43+10.43×44+10.43×1
=(55+44+1)*10.43
=100*10.43
=1043