In multiplications or divisions of any length it is generally convenient to begin by forming a table of the first nine multiples of the multiplicand or divisor, and Napier's bones at best merely provide such a table, and in an incomplete form, for the additions of the two figures in the same parallelogram have to be performed each time the rods are used.
When it is necessary to write the multiplicand before the multiplier, the symbol >e will be used, so that a will mean the same as a X b.
(And Conversely, To Divide By 5, We Multiply By 2 And Divide By Io.) (Ii) In Multiplying By 2, From The Left, Add I If The Next Figure Of The Multiplicand Is 5, 6, 7, 8 Or 9.
The table of multiples will then be as in C. The next step is to arrange the multiplier and the multiplicand above the partial products.
For elementary work the multiplicand may come immediately after the multiplier, as in D; the last figure of each partial product then comes immediately under the corre up to the multiplication of decimals and of approximate values of numbers, is to place the first figure of the multiplier under the first figure of the multiplicand, as in E; the first figure of each partial product will then come under the corresponding figure of the multiplier.
The method E of § ioi being adopted, the multiplicand and the multiplier are written with a space after as many digits (of each) as will be required in the product (on the principle explained in § 1 01); and the multiplication is performed from the left, two extra figures being kept in.