A logarithm table to base 10 can be used to determine the log of the quotient from the parenthetical

fraction (R1/R2) and (T2/T1). Logarithms are divided into two parts, the **characteristic**, which is the

whole number part, and the **mantissa**, which is the decimal part of the logarithm. The characteristic is

determined by the value of the quotient. If this number is 0 to 10, the characteristic of the log is 0. If

the number is 10 to 100, the characteristic of the log is 1, and so on up the scale. The mantissa is

determined by reading down the **N **column of the log table to the value of the first two numbers of the

quotient and across the table to the third number.

As an example, to determine the log of 4.44, we must first determine the characteristic. Since 4 is less

than 10, the characteristic of the logarithm is 0. To determine the mantissa, enter the logarithm table in

the **N **column and read down to 44, then across the table to the column under the 4. Here you read the

mantissa as 6474. Therefore the log of 4.44 is written as 0.647 when rounded off to the nearest

thousandth.

Apply the monitoring data to this formula, using end point dose rates as follow: