1. Three fifths * 7.76 + 0.6 * 1.24 + 60%

1. Three fifths * 7.76 + 0.6 * 1.24 + 60%

=0.6*（7.76+1.24+1）
=0.6*10
=6

1-23-29-227-281-2243-2729=______ ．

1-23-29-227-281-2243-2729，=1-（23+29+227+281+2243+2729），=1-（1-13+13-19+19-127+127-181+181-1243+1243-1729），=1-（1-1729），=1-1+1729，=1729

A few simple math problems for grade six~~~~~~~~~~~~~~~~~~~~
1.3.9/(1.3*5）
2.3.8*43.7+4.12*38+151*0.38
3.40*5%/20%+40
PS: / = division sign * = multiplication sign

3.9/(1.3*5)=3.9÷1.3÷5=3÷5=0.63.8*43.7+4.12*38+151*0.38=3.8*43.7+3.8*41.2+3.8*15.1=3.8*（43.7+41.2+15.1）=3.8*100=38040*5%/20%+40=40*1/4+40=40*(1/4+1)=40*(5/4)=50

Two simple calculation problems in fifth grade: 9.5 times 0.02 times 0.8 times 1.25 (simple calculation) 18.5 + 4.1 + 1.5 + 5.9 (simple calculation) thank you

9.5 times 0.02 times 0.8 times 1.25
=(9.5 times 0.02) times (0.8 times 1.25)
=19 times 1
=0.19
18.5+4.1+1.5+5.9
=（18.5+1.5）+（4.1+5.9）
=20+10
=30

3.5/4.2

3.5/4.2
=（5*0.7）/（6*0.7）
About 0.7, 3.5 / 4.2 = 5 / 6

Find a simple problem 5 / 13 * 11 / 17 + 11 / 13 * 12 / 17

=11/13*5/17+11/13*12/17
=（5/17+12/17）*11/13
=1*11/13
=11/13

A simple problem
1 / 2 + 4 molecules 3 + 7 / 8 + 16 molecules 15 + 32 molecules 31 + 64 molecules 63 + 128 molecules 127

=(1-1/2)+(1-1/4)+(1-1/8)+(1-1/16)+(1-1/32)+(1-1/64)+(1-1/128)
=1+1+1+1+1+1+1-(1/2+1/4+1/8+1/16+1/32+1/64+1/128)
Let a = 1 / 2 + 1 / 4 + 1 / 8 + 1 / 16 + 1 / 32 + 1 / 64 + 1 / 128
Then 2A = 1 + 1 / 2 + 1 / 4 + 1 / 8 + 1 / 16 + 1 / 32 + 1 / 64 + 1 / 64
So a = 2a-a = 1 / 64-1
So the original formula = 7 + 1 / 64-1 = 6 and 1 / 64

A simple calculation
(0.75×3.24+1.67×75%)÷0.75×900×(1-80%)÷3/4

(0.75×3.24+1.67×75%)÷0.75×900×(1-80%)÷3/4
=(3/4×3.24+1.67×3/4)÷3/4×900×(1-80%)÷3/4
=3/4×(3.24+1.67)÷3/4×900×(1-80%)÷3/4
=3/4×4.91×4/3×900×(1-80%)÷3/4
=4.91×900×(1-80%)×4/3
=4.91×900×1/5×4/3
=4.91×1200×1/5
=4.91×240
=(5-0.09)×240
=5×240-0.09×240
=1200-21.6
=1178.4

1+5+9+13+17+.+2009=

First calculate the total number (2009-1) △ 4 + 1 = 503
So = (1 + 2009) × 503 △ 2 = 505515

n=1×5×9×13×17×…… X 2005 × 2009 × 2013, the last three digits of n_______________ . online and other detailed methods, thank you

The last three digits are calculated as follows:
n=1×5=005
n=1×...×9=045
n=1×...×13=585
n=1×...×17=945
n=1×...×21=845
There's a pattern here
n=1×...×25=125
n=1×...×29=625
n=1×...×33=625
n=1×...×37=125
n=1×...×41=125
n=1×...×45=625
n=1×...×49=625
n=1×...×53=125
Obviously, the law is a cycle of {125625125}
25,29,33,37..., 2013 Total (2013-25) / 4 + 1 = 498
498 △ 4 = 124... 2: among the 498 numbers, there are four numbers in one group, 124 groups in total, and two left
So the last three digits of N are the second number in {125625125}, namely 625
n=1×5×9×13×17×…… The last three digits of N are____ 625_____ .