Placing the left index of Ɔ to 222 on D, the two equal coinciding
numbers on Ɔ and D are found to be 4·71.
Note that under the cursor line we have the original number, 22·2, on A,
and from this the number of digits in the root is determined as before.
The plan of finding the square of a number by ordinary multiplication is
often very convenient. The inverse process of finding a square root by
trial division is not to be recommended.
To obtain a close value of a root or to verify one found in the usual
way, the author has, on occasion, adopted the following plan:—Set 1 (or
10) on B to the number on the A scale (L.H. or R.H. as the case may
require), and bring the cursor to the number on D. If the root found is
correct, the readings on C under the cursor and on D under the index of
C, will be in exact agreement.
If 1 on B is placed to a number _n_ on the L.H. A scale, the student
will note that while root _n_ is read on D under 1 on C, the root of 10
_n_ is read on D under 10 on B. Hence, if preferred, the number can be
taken always on the first scale of A and the root read under 1 or 10 on
B, according to whether there is an odd or even number of digits in the
number. Obviously the second root is the first multiplied by √(10).