error to call eight and four thirteen, but it
often may disconcert an immense calculation. Like the pebble in the
shoe, small in itself, it may do great injury. Some years ago there
traveled through the country a genuine "lightning calculator." You could
put down any number, big or little, while his back was turned, and he
would turn again and mark the total with far greater rapidity than he
could speak, and he thought out the total far quicker than he could mark
it. Of course, he had a magic book to sell, but when you came to read
his magic book and see how he did it, you found it was the same old way,
only he was more expert than you. He could add four thousand two hundred
and twenty eight and three thousand six hundred and fifty four as easily
as you could forty two and thirty six, or perhaps four and three, so you
see that the scheme of running up a single column of figures is at best
a clumsy one.

YOU EXPOSE YOURSELF

to additional errors by enlarging the possible additions in a body of
numbers. We are taught the multiplication table up to twelve times
twelve. 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. You see you get an even thirty to
multiply by and load up the sum to be multiplied sufficiently to
balance. Above 5 call it a deficit and go to your next 10 for your body.

I MENTION THESE TRICKS