Objective:

To multiply two values using the CI and D Scales

General:

• Often in multiplication with the C and D one factor goes off scale, requiring resetting to the other index.
• Multiplication using the CI and D scales requires less slide movement and the result index is always on the scale.
• The CI scale is an inverse scale and is read from right to left.
• To multiply with the CI scale, we use the process of dividing by a reciprocal:

Method:

• Move the cursor to the first factor on the D Scale.
• Align the second factor with the cursor on the CI Scale.
• Read the result on the D scale at the relevant CI index.

 

Example 1:  Evaluate 2.46 x 6.95

• Move the cursor to D2.46
• Align CI6.95 with the cursor.
• Read the result D17.1 at CI10

 

Example 2:  Evaluate 3.56 x 4.25

• Move the cursor to D3.56
• Align CI4.25 with the cursor.
• Read the result D15.1 at CI10

 

Practice Questions:  Using the CI and D scales, find the following products.

1. 5.76 x 6.98 (Ans: 40.2)
2. 7.55 x 2.62 (Ans: 19.8)
3. 8.05 x 3.64 (Ans: 29.3)
4. 2.95 x 7.95 (Ans: 23.5)
5. 5.55 x 1.45 (Ans: 8.05)