1. Multiplying several numbers together. For example, suppose it is
desired to multiply 4 * 8 * 6. Place the right-hand index of the C scale
over 4 on the D scale and set the indicator over 8 on the C scale. Now,
leaving the indicator where it is, move the slider till the right-hand
index is under the hairline. Now, leaving the slider where it is, move
the indicator until it is over 6 on the C scale, and read the result,
192, on the D scale. This may be continued indefinitely, and so as many
numbers as desired may be multiplied together.

Example 53: 2.32 * 154 * .0375 * .56 = 7.54




2. Multiplication and division.
Suppose we wish to do the following example:

Example 54:  (4 * 15) / 2.5  = 24

First divide 4 by 2.5. Set indicator over 4 on the D scale and move the
slider until 2.5 is under the hair-line. The result of this division,
1.6, appears under the left-hand index of the C scale. We do not need to
write it down, however, but we can immediately move the indicator to 15
on the C scale and read the final result 24 on the D scale under the
hair-line. Let us consider a more complicated problem of the same type:

Example 55: (30/7.5) * (2/4) * (4.5/5) * (1.5/3) = .9

First set indicator over 30 on the D scale and move slider until 7.5 on
the C scale comes under the hairline. The intermediate result, 4,
appears under the right-hand index of the C scale. We do not need to
write it down but merely note it by moving the indicator until the
hair-line is over the right-hand index of the C scale. Now we want to
multiply this result by 2, the next factor in the numerator. Since two
is out beyond the body of the rule, transfer the slider till the other
(left-hand) index of the C scale is under the hair-line, and then move
the indicator to 2 on the C scale. Thus, successive division and
multiplication is continued until all the factors have been used. The
order in which the factors are taken does not affect the result. With a
little practice you will learn to take them in the order which will
require the fewest settings. The following examples are for practice:

Example 56: (6/3.5) * (4/5) * (3.5/2.4) * (2.8/7) = .8

Example 57: 352 * (273/254) * (760/768) = 374

An alternative method of doing these examples is to proceed exactly as
though you were multiplying all the factors together, except that
whenever you come to a number in the denominator you use the CI scale
instead of the C scale. The reader is advised to practice both methods
and use whichever one he likes best.

3. The area of a circle. The area of a circle is found by multiplying
3.1416=PI by the square of the radius or by one-quarter the square of
the diameter

Formula:
A = PI * square( R )
A = PI * (square( D ) / 4 )

Example 58: The radius of a circle is 0.25 inches; find its area.

Area = PI * square(0.25) = 0.196 square inches.

Set left-hand index of C scale over 0.25 on D scale. square(0.25) now
appears above the left-hand index of the B scale. This can be multiplied
by PI by moving the indicator to PI on the B scale and reading the
answer .196 on the A scale. This is an example where it is convenient to
multiply with the A and B scales.

Example 59: The diameter of a circle is 8.1 feet. What is its area?

Area = (PI / 4) *  square(8.1)
     = .7854 * square(8.1)