you need
  • - formula for the transition from one base to another logarithm;
  • - four digit mathematical table Bradis.
Guide
1
Bring the log to the standard form, if its basis is not equal to 10. Use the formula for the transition from one base to another.
2
find the characteristic of the logarithm.If the number is greater than or equal to one, then count the number of digits in the integer part of the number.Subtract this amount from the unit and get the property value.For example, the logarithm of the number 56.3 characteristic is 1. If the number is a decimal fracti
on less than 1, then count the number of zeros in it until the first digit different from zero.Make poduchennoe negative value characteristics.For example, the logarithm of the number 0.0002 characteristic is -4.
3
Determine the number to find the mantissa as a whole.Ignore the comma in this including, if any, and give up all zeroes at the end of the number.Decimal point in decimal and trailing zeros does not affect the value of the mantissa.Record the resulting integer.For example, the logarithm of the number is equal to 56.3 563. Depending on the number of digits contained in this number depends on the algorithm works with a four tables.There are three types of algorithms.
4
Find mantissa of the logarithm of following these steps, if the number of its location is a three-digit.Find the four-mathematical tables Bradis table XIII «Mantissas logarithms."Click the line containing the first column «N» the first two digits of the number by which the mantissa is sought.For example, if we have the number 563, then look for the line where the first column is 56. then promote the right of this line to its intersection with the column, the number of which coincides with the third digit of the original number.In this example, the column with the number 3. At the intersection of the row and column found is the mantissa.Mantissa found in the number of 563 is equal to 0.7505.
5
Find mantissa of the logarithm of following these steps, if the number of its location has two or one digit.Assign mentally to this number is the number of zeros to make it to three.If the number is 56, it turns 560. Find mantissa of the resulting three-digit number.To do this, follow the steps from step 4. The mantissa of the number 560 is equal to 0.7482.
6
Find mantissa of the logarithm of following these steps, if the number of its finding is four-digit.Find the mantissa for the number shown by the first three digits of the number.To do this, follow the steps from step 4 is then moved along the horizontal line of the mantissa found in the right-hand side of the table, located behind the vertical thick line and containing the amendments to the fourth digit.Find in a column with the number of amendments, which coincides with the fourth digit of the number.Add the amendment, located at the intersection of row and column to the mantissa found on the three-digit number.For example, if the number is equal to find mantissa 5634, the mantissa of 563 is equal to 0.7505.Amendment 4 on the figure 3. The final result is equal to 0.7508.
7
Find mantissa of the logarithm of following these steps, if the number for it contains more than four digits.Round the number up to four digits, so that all the numbers, starting with the fifth, were zeros.Drop the last zeros and get the mantissa of four-digit number.To do this, follow the steps from step 7.
8
find the logarithm of the number as a sum of characteristics and mantissas.In this example, the logarithm of the number of 56.3 is 1.7505.