 Hello and welcome to the session. In this session we will discuss the logarithms and empty logarithms from tables. First of all we discuss to find the logarithms on tables. This is a form of a logarithm table which is divided into three sets of columns. Three left column that is this column is headed by a vacant square and in this column we have the numbers from 10 to 99. Now we make the columns which are headed by the numbers 0, 1, 2, 3, 7. Then the next set of columns is where the mean difference in which we have nine columns headed by the numbers 1, 2, 3, 4, 7 is we need to find log of 841.7 from the this before the decimal point. So 3 minus 1 that is 2 would be the characteristic. 2.7 would be equal to the mantissa and we will now find the mantissa from the logarithm table. To find the mantissa we will consider the number without the decimal point that is 8417 that would be look for the number. The first two digits from the left this number is we will move in the row of 84 and we will find the number under the column of 1 and in the row of 84 and that number is 9248 and the number as 9248. In digit 1 we have the digit 7 in the column of 7 in the column of mean differences and here the number is where we find the number to be 4. These two numbers that is 9248.7 is equal to 2.92 find the log of any number using the logarithm tables. The empty logs from the tables x to the base a is equal to k that log of 841.7 is equal to 2.92 the empty log of 2.92 the same as the logarithm tables that is also divided into three similar sets of columns and 0.9252 is the mantissa. To this take we will consider the mantissa 0.92 three left column and the column added by 5 we find the number to be 8414.92 the number that we get is these two numbers that is 8414 and 4 which is equal to 8418. Quiet number which is the empty log from here we will move three digits keep the decimal point here 2.9252 is equal to 841 also given number using the tables. The characteristic that is 2 bar and we will consider the mantissa part that is 0.06 four digits after 6 that is the empty log to the decimal point so we have 0.011 and 0114. 06 is equal to 0.011 the empty log of the number minus 1.3915 this is written as minus 1 minus 0.3915 is negative so we cannot find the empty log in this case as the mantissa is negative and the fractional part of the number so this is equal to minus 1 minus 1 minus 0.3915 plus 0.6085 which is equal to so this means we need to find is same as minus 1.3915 we already know how to find out the empty log for such numbers 0.0406 minus 1.3915 is same as 0.04060 we cannot the mantissa part is negative positive we need to add and subtract 1 between the integral and the fractional parts of the given number so it is the fashion hope you have understood how to find the logs and empty logs from the tables