What are the approximate numbers in the newspaper? Please list ten

What are the approximate numbers in the newspaper? Please list ten

example:
(1) The output value of a factory in 2011 is about 15 million yuan
(2) The average height of class 2 in Grade 1 is about 1.57 meters and the average weight is about 50.5 kg;
(3) The circumference of a circle with a diameter of 10 cm is 31.4 cm;
(4) In 2010, the national economy grew by 7.8%
The net value is 15 million yuan
31.4 π
Pass rate 7.8%

The price of a commodity will be 99 yuan after 10% price increase and 10% price reduction. What is the original price of the commodity?

Suppose the original price of the goods is x yuan
x×(1+10%)×(1-10%)=99
x×1.1×0.9=99
X = 100 yuan
A: the original price is 100 yuan

The inverse number of 1 to the power of 2010 - (1-0.5) times one third times {3 - [(- 3) squared]}

The inverse number of 1 to the power of 2010 - (1-0.5) × 1 / 3 × {3 - [(- 3) square]}
=-1-0.5×1/3×｛3-9｝
=-1-0.5×1/3×｛-6｝
=-1-0.5×｛-2｝
=-1+1
=0

First year's Mathematical Olympiad, good bonus points! (to write the process ah!)
（1）1-3+5-7+9···+97-99
(2) The rational number represented by point a on the number axis is - 3, the distance between point B and point a is 5, find the rational number represented by point B? The distance between point C and point a is a, find the rational number represented by point C?
Hurry up!

1-3 + 5-7 + 9 ··· + 97-99 = (1-3) + (5-7) + 9 ··· + (97-99) = - 2 × 50 / 2 = - 2 × 25 = - 50 on the number axis, the rational number represented by point a is - 3, the distance between point B and point a is 5, find the rational number represented by point B? The distance between point C and point a is a, find the rational number represented by point C? | B-A | = 5, a = - 3B = - 8

A certain commodity is sold at a 20% discount, which means that the price is lower ()
A. 80% B; 20% C; 1 / 8 D; 1 / 4 d

B

How accurate is 029 thousand? How many significant numbers are there? How to write the scientific counting method of the 5th power of 3.89 * 10? How accurate is 029 thousand? How many significant numbers are there?

029 to ten
The scientific counting method of the 5th power of 3 * 10 remains unchanged, accurate to thousands, with three significant numbers

8 (2x-5) power = 27 (1-x) power = 64 (x + 3) power + 27 = 0
On the speed of three refueling urgent

8(2x-5)³=27
2(2x-5)=3
2x-5=3/2
2x=6+1/2
x=3+1/4
(1-x)³=64
(1-x)=4
x=-(4-1)
x=-3
(x+3)³+27=0
（x+3)³=-27
（x+3）=-3
x=-6

As shown in the figure, in the square ABCD, e and F are the points on the edge of BC and CD respectively. AE, De, BF and AF divide the square into 8 small pieces, and the area of each small piece is S1, S2 Compare the size of S3 and S2 + S7 + S8, and explain the reason

Reason: as shown in the figure, the area of S3 in the figure S3 = sabcd-s △ abe-s △ bcf-s △ cde-s △ ADF + S2 + S7 + S8 is reduced to S3 = BC ·cd-12 × (be + EC) × cd-12 × (DF + FC) × BC + S2 + S7 + S8 ∵ BC = CD, ∵ BC ·cd = 12 × (be + EC) × CD + 12 × (DF + FC), so S3 = S2 + S7 + S8

12 out of 16 and 27 out of 36; 8 out of 5 and 13 out of 16; 5 out of 3 and 77 out of 49,
Good answer, price recovery

12/16=3/4=27/36=3/4
5/8=10/16>13/16
77/49=11/7=33/21,5/3=35/21>33/21,
5/3>77/49

The 50 data are divided into 5 groups to list the frequency distribution table. The frequency of the first group is 6, and the sum of the second group and the fifth group is 20. Then the sum of the frequency and the sum of the frequency of the third group and the fourth group are ()
A. 20；0.4B. 24；0.48C. 26；0.52D. 31；0.62

The sum of frequency of the third group and the fourth group: 50-6-20 = 24, the sum of frequency: 24 △ 50 = 0.48, so select: B