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LOG TABLE (FINANCIAL MATHEMATICS) - MATHEMATICS B.COM CLASS 12 - YouTube
Channel: SHOEB MASROOR - Aligarh's No.1 Commerce Channel
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Hello friends! Welcome to the channel
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We were on the chapter financial mathematics
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and today we will learn about Log and Anti log
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It is very important to learn log and anti-log
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as it makes the calculations very easy
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Firstly, we will start with Log and log table
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I will show you the log table
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This is log table
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With the help of log table we have to find the value of log
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Let’s understand how to see log table
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First point is, in log we can see values up to 4 digits
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Let’s take an example
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Suppose we are given log 1234 and we have to find its value
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The first thing we have to understand is to check how many digits are given in the question
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Maximum digits can only be 4 and here in the question also 4 digits are given
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First we have to count the total digits given and subtract 1 from it
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So 4 – 1 would be 3
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Then put a point after it
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After that we will write the answer
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Let’s see how to write the answer
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We are given 1,2,3 and 4
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We will check the starting two digits in the Main column
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Third digit in the difference column
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And fourth digit in the mean difference
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I will show these columns in the log table
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This is log table
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The first column where two digits are written is known as Main column
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The next column starting from 0 to 9 is called as differences column
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And the last column from 1 to 9 is called as mean differences column
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Understood ?
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first one is Main , From 0 to 9 Differences
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And From1 to 9 , Mean Differences
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Now we have to find the value of 1234
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I have already told you to see the starting two digits in the mean column
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And the third digit in the differences column
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Let’s see 12 on 3 in the log table
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In the first column it is written 12
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We will see 12 in the third column
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We got 0899
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0899
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So we have used three digits till now
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Now we will use the last digit i.e., 4
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We will check 12 on 4 in the mean difference column
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Let’s check in the log table
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This is mean difference column
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We will check 12 in the 4th column whose value is 14
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Now we will add 14 to 0899
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We got 0913
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Now we will write this value here
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We got 3.0913
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So the value of log 1234 is 3.0913
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Let’s take one more example
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Lets See the Different Cases
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So we have already solved log 1234 whose value is 3.0913
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Here we got 3 as there are four digits so 4-1 = 3
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Then we checked 12 on 3 in the log table and then 12 on 4
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Then we added them up and got the answer
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Now let’s take another case
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Log 123.4
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I have already told to count the total digits and subtract 1 from it
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We have to check the digits before point
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Here we did not have a point which means point is after 4
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Now we will count the digits for log 123.4
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Here point is after 3 which means we have 3 digits
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So 3-1 = 2
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Put a point after 2
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Now we have to follow the same procedure
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Now we will check 12 on 3 and then 12 on 4
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We got the answer as 2.0913
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Now if we consider the next case log 12.34
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There are only two digits before point
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So 2-1 = 1
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We got 1.0913
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Here, we saw that the values are not changing after point
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Only the digit which is prior to the point is changing
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Now in case of log 1.234
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There is only one digit before a point
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So 1-1 = 0
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We got 0.0913
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In the next case log 0.1234
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We do not have any digit before point
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So, 0-1 = -1
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We got -1.0913
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This is the method to use log table
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First, we have to subtract 1 from the total digits given
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Then we will check starting two digits in the main column
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Third digit in the differences column
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And the fourth digit in the mean difference column
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After adding them, write their value
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Let’s take some more cases
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Now we have Log 152
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Here we have only three digits
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So, 3-1 =2
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Put a point after 2
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Now check 15 on 2
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This is 15 in the main column
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and 2 is in the Differences
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This is 15 in the main column
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We got 1818
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We will write the value here
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The answer is 2.1818
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Now let’s see for log 1.52
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The answer is 0.1818
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Because the digit before point is 1
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So 1-1 = 0
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The answer is 0.1818
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Now suppose we are given log 46
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Now we will calculate its value
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Here we have only two digits
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So 2-1 = 1
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so our answer will be 1 point something
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Now how will we check it in the log table?
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We will simply see 46 on 0
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as we can add as many zeroes as we want after decimal it won't affect the value
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We will simply see 46 on 0
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We got 6628
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So the answer is 1.6628
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Let’s take one last case
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if we have
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Log 4
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Log 4
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want to try it yourself ?
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Here, only one digit is given
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So 1-1= 0
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Now we will put .0 after 4 as we can add as many zeroes after putting a Decimal
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But we need Maximum 4 or Minimum 3 Digits
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We will put two zeroes after 4
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we can use log table with these 3 digits
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as we need only 2 digits for the main column
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and 3rd digit is for difference column
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Now we will check 40 on 0 in the log table
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We got 6021
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So the answer is 0.6021
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Okay then! I will give you a small recap again
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so that you will never forget it
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First of all, we can check values up to 4 digits
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We will check starting two digits in the mean column
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Third digit in the differences column
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Fourth digit in the mean difference column
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We will write the values after checking third digit at one place
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Then the values obtained after checking the fourth digit will be written separately
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And then add both the values
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Then We will get the answer
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So number of Digits minus 1
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The value Put Decimal
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Locate again the fourth digit in the Log Table
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I hope you have understood log as it will be very
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helpful in the upcoming questions
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related to compound interest and annuity etc.
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Today we have learned about log table
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but it is also important to learn about the properties of log
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Because both log table along with its properties are used to provide a solution for any question
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We have covered Log Table in this Lecture
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I will provide a link for log properties and you can easily understand it from there
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In the next class we will discuss Anti- log
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and only after understanding Log and Anti log We will be
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capable of solving questions of FINANCIAL MATHEMATICS by applying these two.
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Do not forget to subscribe this Channel
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Will meet in the next class!
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Thanks for watching!
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