Website last updated 03 August, 2010

B Scale

The A and B scales are for finding squares and square roots, when used in conjunction with C and D. B is identical to A except that A is found on the stock, and B is found on the slider.

read the tutorial on squaring, cubing, and roots
B ( and A ), is just a C or D scale, shrunk to 1/2 its length and copied to the right with values 10x higher. This marks off the squares of the numbers on C or D. We call 1 to 10 the left decade, and 10 to 100 the right decade*. It's easy to find the coefficient of squares and square roots with A or B, but more care must be taken to determine the correct power of ten, and to choose the correct decade.( decimal point ).
A warning about multiplication with A and B
A and B are found on most slide rules, and since they are logarithmic scales, they can also be used for multiplication and division. In fact, you'll go off the scale less when multiplying with A and B. There are several reasons not to get into this habit:
  1. A and B are compacted to half the length of C and D, thus they offer less precision.
  2. Other scales all make reference to C and D - you'll have to remember a number and reset slider and cursor more often if you multiply with A and B.
  3. You can't use the algorithm found in Setting the Decimal Point when multiplying or dividing with A and B.
Notes: 1. These are just warnings - go ahead and multiply with the A,B scales if you want to. The results will still be correct, just less precise and convenient. 2. The same warnings apply to using two K scales to multiply.

* It's strange that these divisions are called "decades", like the ten-year time interval. Multiplicative log scales, which lack zero, have only nine intervals per decade.