New-York tribune., 1906-11-04

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Very well, then said Uncle Bob, do
/ Just as | tell YOU. You and Fred each write
on Your paper a row of figures
30 Lucy wrote 5, o, 5, ?, I, !; and Fred
wrote !, 3, !, o, :, o, I, !.
Now, then, went on Uncle Bob, add up
those digits in your head, and subtract the
sum from Your original number
So Lucy added up her dgts and found
they came to -. Subtracting this from her
original number, she had left S65.IQo; while
Fred, whose digits added up to -. subtracted,
and had remainder OF 45,7oS,572.
Now strike out one figure from your
answer" said Uncle Bob, and write on an
other slip OF paper your answer with that figure
omitted"
In a moment Lucy had struck out the figure
and handed her uncle the slip Of paper. on
which was written $500.
After a brief glance at it, Uncle Bob said
quietly, You struck out the figure o."
50 | did, sad Lucy, opening her eyes in
Meantime Fred had struck out of his
answer, and offered for his uncles inspection
the figures 4,37Q,572.
You crossed of 81 said Uncle Bob.
Il did 50" said Fred. Please try it
again
So they tried it again, and this time when
the children were about to present their lines
OF figures to him for inspection, Uncle Bob
said, - Nou may write the lines of figures as
You have them, or You may write them back
Lucy reversed her line of figures and gave it
to her uncle; but Fred gave his just as he had
1t on his own paper.
1t seemed to make no difference; for Uncle
Bob told them instantly what figures they had
crossed out.
them still further, Uncle Bob told them that
they might tumble their figures all up, and as
long as they kept the real figures they had
they might offer them to him in any rotation
This time Lucy's original row had read
9, ?, ;, 9, !, s, I.
The sum of these digits was 81. and conse-
quently, after subtracting, she had o,236,44S.
She struck out one of the 4 S and mixed up the
Others, so that they stood S63,o+2. This row
she handed TO her uncle, who Immediately told
her that she had crossed off a !.
Fred had taken short number this time
He had put down only Q, 3. >, I, !. These
digits amounted to 10. After subtracting,
he had remaining 63,roS. He crossed out the
Q. and, mixing up the Others, gave his uncle
the row, I,6S3.
Uncle Bob looked at it abstractedly. Then
he closed his eyes. Il seem to see a float
ing in the air" he said. Il think, my boy,
you crossed off o.
No, SIR cried Fred triumphantly
"Ah, wait" said his uncle placidly; Il
spoke too hastily. | see there is tail to the
o which had escaped my notice. 1t was a o.
Yes, sir, | did" said Fred, laughing
" Please tell us how to do it
| wish for once you children would guess
a puzzle yourselves" said Uncle Bob; but
| suppose you never WILL SO I'll tell YOU. It's
really very simple when you know how.
Well, he continued, after the line is
written down, and the sum of its digits sub
tracted, and a single figure crossed off, YOU
have row of figures handed to YOU You
must mentally add these and subtract their
sum from the next multiple of Q. That sounds
complicated; but 1t IS not at all If the sum
OF the figures given you adds up to 3 the
next multiple OF Q is p, and the number YOU re
III search of is T. If the row of figures adds
up to so, the number struck out was o. because
that added to 80 makes IS, which is the next
multiple of 0. Do you understand"
Yes said Lucy, wrinkling her forehead :;
you just add the figures given YOU, and sub
tract that from whatever comes next
higher IN your nine times multiplication
table"
That's right" said her uncle, and the only
time the rule won't work IS when the number
crossed out IS either o or a O. As you
can see for yourselves, if the digits added up
to -, YOU wouldn't know whether a o or a 0
had been crossed out because either of those
added TO = would result in Il multiple of o."
Oh said Fred, that's why YOU made up
that yarn about the tail to the o."
Yes" said Uncle Bob, and though you
may work that little ruSe once, if YOU are cor
nered second time it is better to own up
frankly that IL either a Q or a O. and