Page:Methods of Operating the Comptometer (1895).djvu/13



After a little practice one can carry two figures of the multiplier at once with the index finger of each hand, striking alternately, and by so doing increase the speed 50 per cent.

Considerable time can with profit be devoted to the following finger exercises, because two fingers are used a great deal, especially in division and multiplication. In practicing this method run fast, do not be too cautious, and you will soon acquire the right stroke.

Strike 74,000,000 five times, using the index finger of the left hand in striking the 7, and the index finger of the right hand in striking the 4; striking them alternately, allowing one finger to be raised entirely off one key before depressing another; raise the fingers one-fourth of an inch off the keys each stroke. Move both fingers one key to the right and strike five times; continue moving to the right one column at a time across the machine, striking the keys five times each. Do the same thing with 36, 45, 63, 54, 18, 81, 92, 47 and 58. At first it will be difficult to strike the keys rapid and also each independently and in proper time. It is to teach this, the proper key stroke, that this exercise is given. Avoid the tendency to strike keys in jerky time like this, .. .. .. .. .. .. but strike them regular like this......................

and the multiplier is not greater than 9, to avoid taking it off, it can be conveniently multiplied by using the number one less than the multiplier, for example: we are required to obtain 4263 x 64 x 8. After multiplying 4263 by 64 as illustrated above, 272832 appears on the register as the result. To multiply this amount by 8, without turning the machine to naught, take the row of keys next lower than 8 the multiplier, (the 7's,) and beginning at the left of the multiplicand over the hundreds of thousands, strike twice, as 2 is in that order on the register; then moving to the right one column, strike seven times, as 7 is in that order; two times in the next order to the right, as 2 is in that order, etc., until all the keys have been struck as many times as the corresponding figures on the register indicate. The product, 2182656, will then appear on the register.

deduct one from the multiplier and then proceed to strike it on the keys by striking each figure of the multiplier alternately (using the index finger of each hand), and working from the left of the multiplicand just the same as in the example illustrated above.

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