To use the Pickett Deci-Point slide rule, it is necessary to know some of the terminology associated with the calculations which need to be carried out. The terms used in the calculations as digits (D), zeros (Z) and factors (F) which we will now explain.

Calculating the number of factors for the numerator or denominator is a simple process just requiring use to count how many there are in each.

e.g. In the expression; 3400 x 0.0904, there are two factors. This simple process is carried out for both the numerator and denominator.

The term digits refers to the total number of digits in front of the decimal point. In doing this we consider the numerator and denominator separately.

e.g. Consider the numerator of the expression first;

The number 76600 has 5 digits in front of the decimal point and 450 has 3 digits in front of the decimal point giving a total of 8. Since 0.0345 is less than 1, we only count the zeros behind the decimal point, so this gives us 1. Hence for the numerator;

F = 3, D = 8 and Z = 1

In the denominator the number 3,850,000 has 7 digits in front of the decimal point and 0.0000555 has 4 zeros behind the decimal point. Hence for the denominator;

F = 2, D = 7 and Z = 4

The calculations required will then use these values to enable the location of the decimal point in the answer. This will be illustrated in the examples which follow.

Proceed to Multiplication Example