We never stumble up to that point. But it ought to continue up
to one hundred times one hundred. We could then always add two figures
to two figures easier then to parcel the operation out into two jobs.
The "lightning calculator" had probably carried it up to five thousand
times five thousand. Take an interest in "sums." Learn
THE FREAKS OF FIGURES.
For instance, to multiply any set of figures by 11--say 54--add the 5
and 4 together and put the 9 between the 5 and the 4. To multiply 1, 2,
3, 4, 5 and 6 by 11, do the same way, only carry your 10's. Thus 6 and 5
are 11, put down 1 before the 6; 5 and 4 are 9 and 1 to carry is 10; put
down the before the 16, etc. Again to multiply, say 18 9's by 9, bring
down a 1, then make 170's and a 9 out to the left. Again to square
numbers, call even 10's the body; call the rest the surplus,--104--add
surplus to body making it 108; now square the surplus (4) making 16 and
put it after the 108, or 10,816. This is simply taking advantage of the
10s. Take 33 and you will see. Here 3 is the surplus; add the surplus,
making 36; multiply 36 by 30, making 1,080; square the surplus, 3 times
3--9; add to 1,080--making 1,089.
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