Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-11-04

very well, then" said Uncle Bob, do
just as l tell you. You and Fred each write
on your paper row of figures"
So Lucy wrote 8, g, 3, ?, I, 4 and Fred
wrote 4, 8, !, 9,S 6, IA.
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 digits, and found
they came to "a. Subtracting this from her
original number, she had left S63,I9o; while
Fred, whose digits added up to az, subtracted,
and had a remainder of 43,7oS,572..
Now strike out one figure from your
answer" said Uncle Bob, land write on an
other slip of paper your answer with that figure
In moment Lucy had struck out the figure
6 and handed her uncle the slip of paper on
which was written $1,000.
After a brief glance at it, Uncle Bob said
quietly, You struck out the figure g."
SO | didf' said Lucy, opening her eyes in
amazement.
Meantime Fred had struck s out of his
answer, and offered for his uncle's inspection
You crossed sset of off s." said Uncle Bob.
81 did So 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, =" Gou may write the lines OF figures as
you have them, or you may write them back
ward, and you need not tell me which,
Lucy reversed her line of figures and gave it
to her uncle; but Fred gave his just as he had
it on his own paper.
1t seemed to make no difference; for Uncle
Bob told them instantly what figures they had
crossed out.
Then they tried it third time, and to puzzle
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, 2, 3, E, A. 8, I.
The sum of these digits was 80, and conse-
quently, after subtracting, she had o,236,44S
She struck out one of the As and mixed up the
others, so that they stood S63,942. 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 g. g., 2, I, T. These
he had remaining 63,1oS. He crossed out the
| 9, and, mixing up the Others, gave his uncle
| the row, 1858.
Uncle Bob looked at it abstractedly. Then
he closed his eyes. Il seem to see float
ing in the air. he said. Il think, my boy,
you crossed off a o.
"No, sirr' cried Fred triumphanty.
"Ah, wait said his uncle placidly; 81
spoke too hastily. l see there is tail to the
which had escaped my notice 1t was a 9"
YES, Sir l did," said Fred, laughing.
Please tell how to do it.
6 wish for once you children would guess
a puzzle yourselves" said Uncle Bob but
l suppose you never will, so I'll tell you. It's
really very simple when you know how
WELL" he continued, latter the line is
written down. and the sum of its digits sub
tracted and a single figure crossed off, you
have a row of figures handed to you. You
must mentally add these and subtract their
sum from the next multiple of 9. That sounds
Compicated; but it is not at all. If the sum
of the figures given you adds up to 20, the
next multiple of is Fl, and the number you re
in search of is 4. If the row of figures adds
up to 80, the number struck out was 6, because
that added to 80 makes As, which is the next
multiple of 9. Do you understand"
Yes" said Lucy, wrinkling her forehead
"you just add the figures given you, and sub
tract that sum 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 a 9 o. AS you
can see for yourselves, if the digits added up
to as, you wouldn't know whether Q or a o
had been crossed out, because either of those
added to As would result in multiple of O."
oh" said Fred, that 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 a second time it is better to own up
frankly that it was either a Q or a o, and
you don't know which. Never act as if YOU
were adding the figures or calculating result.
The charm of all these tricks is to appear to