45 5 is revised to two significant digits whatever

Keeping two significant digits is 46

Significant figures. From the first non-zero digit to the left of a number to the last digit, all digits are significant digits for that number.

It is a number from the first non-0 number on the left to the last number, all digits (including 0, scientific notation.

Not counting 10 to the nth power), which is called a significant figure. To put it simply, remove all the zeros in front of a number and start with the first positive integer.

Up to the exact digits, all are significant digits.

For example, the first two zeros are not significant figures, and the following 109 are significant figures (note that the middle 0 is also counted).

Multiplied by 10 to the 5th power), 3 1 0 9 are significant figures, and the following 10 to the 5th power is not a significant figure.

Only 5 and 2 are significant figures.

The first two zeros are not significant figures, and the following 230 are significant figures (the following 0s are also counted).

There are 3 significant figures.

There are 7 significant digits.

multiplied by 10 to the power of 4), 3 significant figures are reserved.

Logarithm. Significant figures are all digits after the decimal point, e.g. log x = significant figures are, log a = significant figures are .,5, ph = significant figures are.

Directly add a 0 to the end, and the significant number is not two figures.

Summary. Hello, from the first non-0 digit to the left of a number, to the last digit, all digits are significant digits of this number.

It is a number from the first non-0 number on the left to the last digit, all digits (including 0, the nth power of 10 is not counted in scientific notation), called significant digits. To put it simply, remove all the 0s in front of a number, and everything from the first positive integer to the exact digit is a significant digit.

Revised to three significant figures.

Hello, from the left side of a number to the non-0 number from the early defeat to the last digit, all the numbers are the significant digits of this number. It is a number from the first non-0 number on the left to the last digit, all digits (including 0, the nth power of 10 is not counted in scientific notation), called significant digits. To put it simply, remove the 0 in front of a land number, and all the digits from the first positive integer to the exact digit are all significant digits.

In this question, 253541 is a significant number, and when three digits are reserved for 254, they are also rounded, and the final answer is.

If you are satisfied, you can give a thumbs up and encouragement.

I wish you a happy life [Bixin].

Thank you.

Summary. First we need to calculate the concentration of the Na2CO3 solution. The molar mass of Na2CO3 is g mol, so Na2CO3 is equivalent to mol.

According to the chemical equation of Na2CO3 and HCl, it can be obtained: Na2CO3 + 2HCl 2NaCl + CO2 + H2O It can be seen that 1 mol of Na2CO3 can neutralize 2 mol of HCl. So the molar concentration of HCl contained in HCl solution is:

1 ml g) 1 mol g) = mol ml Substituting the above results into the equation yields: mol Na2CO3 2 HCl mol ml) = mol Na2CO3 Therefore, the mass fraction of Na2CO3 in this sample is: ( mol Na2CO3) g 1 mol Na2CO3) g 100% = So, the Na2CO3 content is.

The revision of the three significant figures is.

According to the rule of significant figures, three significant digits should be retained after the amendment, so it is necessary to determine whether the first four digits such as four digits are rounded or rounded. When the fourth digit is 5 or greater than 5, it will be carried forward; If it is less than 5, it will be rounded. In this problem, the fourth digit is 5, so it needs to be carried by Sennai, at this time, the third digit 2 plus 1 gets 3, and the fourth digit is left with 0, and the result after the revision is.

When I went to look up the answer, I found it.

There is also a 5 rounded off after the kiss.

Okay thank you. Okay

How to do question 21 in this?

The content of Na2CO3 is:

How? First we need to calculate the concentration of the Na2CO3 solution. The molar mass of Na2CO3 is g mol, so Na2CO3 is equivalent to mol.

According to the chemical equation of Na2CO3 and HCl, it can be obtained: Na2CO3 + 2HCl 2NaCl + CO2 + H2O can be seen to neutralize 2 mol of HCl. So the molar concentration of HCl contained in HCl solution is:

1 ml g) 1 mol g) = mol ml Substituting the above results into the equation yields: mol Na2CO3 2 HCl mol ml) = mol Na2CO3 Therefore, the mass fraction of Na2CO3 in this sample is: ( mol Na2CO3) g 1 mol Na2CO3) g 100% = So, the content of Na2CO3 in the hall is .

Summary. So covenant is equivalent to covenant revision.

Revise to two significant figures.

Hello, glad to answer for you, the first answer is.

Second, the specific analysis is as follows.

Revise to two significant figures.

The first step is to keep two significant digits, which is to keep two decimal places, and the third decimal place can be retained according to rounding.

Approximately equal to, ? Mathematics has not been repaired, and the term ha is mathematics.

Covenant Amendment* is about equal to Ha.

Jiangsu Province does not have this concept, sorry, I will check the amendment, that is, the covenant here is equal to.

What are the two significant digits that are reserved.

To reduce the two significant figures is to look at the third decimal place, if it is less than 5, round off.

Greater than 5 into one.

The answer is the same, yes.

is a meaning method as well, because the third decimal place is 5

Therefore, the principle of further 1 is adopted.

So covenant is equivalent to covenant revision.

Aren't those two significant figures 93?

The textbook example is as follows: The following hidden oak numbers are all revised to two decimal places in the row, and the end of the file is:

Significant figures refer to the decimal part, not the integer part, if it is 95, how to keep one decimal place 9? Obviously unreasonable.

Revise to one significant digit, so the significant digit is reserved for the decimal part.

What are the significant figures.

It's the decimal part to which digit is exact.

Keeping two significant digits is to put it another way of saying it is precise.

The significant digits are counted from the first non-zero number on the left to the last digit.

Keeping significant figures and asking what significant figures are is not a concept ha.

The first revision of the two significant numbers of the answer is 94 Second, the textbooks of each region are indeed different Ha went to study it, the correct answer is But it is not 93 is 94, because there is a blind early position to check the god pants is 5 to take into 1, the principle of revision of the significant number is the first not 0 to the last defeat Jane one, 93 is followed by 5 need to enter 1, become 94

Second, the specific reference materials are as follows: on pages 10-11.

According to the local textbook, the general requirements of the revision textbook are to repair and sell the two significant digits in the same meaning as the rolling dates and the significant digits, in summary, the answer is 94, because the last digit of 3 is 5, and it needs to be 1, and it becomes 94, specifically refer to pages 10-11 of the textbook.

Effective hunger before touching the number: from the first non-0 number on the left side of the rotten talk, to the last digit, all the numbers of this number have regret effect numbers. in this question.

If the significant digits are kept to 4, they can only be kept to the 4 digit, and 4 is followed by 5, which can be entered.

So it turned out to be.

Summary. Approximate General Index Value Revision Rules. The numerical modification rule refers to the process of omitting the last few digits of the original value and adjusting the last digit of the retained value before performing specific number operations, so that the final value is closest to the original value.

The specific rules that guide numerical revisions are known as numerical revisionist rules.

Approximate General Index Value Revision Rules. The numerical modification rule refers to the process of omitting the last digits of the original value and adjusting the last digit of the reserved value before the specific number of the trapped potato is calculated, so that the final value is closest to the original value. The specific rules that guide the numerical revision are known as the numerical rules of filial piety.

After reducing the repair to two digits, its repair value.

For , , and 5, the median is .

The interval of 5 repairs, that is, the width of the hole will be brightened, and after the repair is completed, it will be attacked, and then divided by 2, and it will be obtained.

Summary. Hello, extended information: 1. When the n significant digits are retained, if the n+1 digit 4 is discarded.

2. When the n-digit significant digit is retained, if the n+1 digit is 6, the n-digit digit is retained when the n-digit significant digit is retained, if the n+1 digit = 5 and the following digit is 0, then the nth digit is even, the following digit is rounded, and if the nth digit is an odd number, add 1; If the n+1 digit = 5 and any number that is not 0 after it, add 1 regardless of whether the nth digit is odd or even. For example: Reserve 3 significant digits = Reserve 3 significant digits = Reserve 3 significant digits = <>

<> revise the digits to four significant digits.

<> revise the digits to four significant digits.

Hello, the 4 significant digits are: Oh. <>

Hello <>, because the 4 significant digits are pure deniers to be counted from the decimal point. So the number does to disturb the four significant digits are: Oh. <>

Smile and stare at <>

<> you're not right.

Hello, that's right! Although the last digit is 0, the title requires that you keep 4 significant digits up, so the auspicious old 0 should be written. <>

Brother Smiling Ling] <>

<> hello, expand the ingredients of the capital bureau: 1. When the n digits are retained, the effective random finger number, if the n+1 digit 4 is discarded. 2. When the n-digit significant digit is retained, if the n+1 digit is 6, the n-digit digit should be retained as the n-digit significant digit, if the n+1 digit = 5 and the following digit is 0, then the nth digit if it is even, the following number will be rounded, and if the nth digit is the number of chira, add 1; If the n+1 digit = 5 and any number that is not 0 after it, add 1 regardless of whether the nth digit is odd or even.

For example: Reserve 3 significant digits = Reserve 3 significant digits = Reserve 3 significant digits = <>