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Four kids got all February Math Mania
answers
With the return of the number puzzles as February's Math
Mania questions, the number of entries increased.
And, the number of kids who got all the answers correct also
increased.
Four of you answered all five puzzles correctly. The winners
were Beth Johnston, Rebecca Meyer, David Kirner and Danny
Sommer, all of St. Louis.
Under Young Saint Louis.com rules, up to three $10
Borders' gift certificates are awarded for all-correct entries.
Because Beth already has been a two-time winner of Math
Mania, we awarded book certificates to the other three
February winners.
The two puzzles that gave entrants the most trouble were
questions No. 3 and 4.
In No. 3, about the different ways to get change in paper
money for a $20 bill, most answers were too low. In No. 4,
about the number of map colors, most were too high.
One of the kids with all correct answers, David Kirner,
didn't leave anything to chance on No. 4. He had the correct
answer, which was four colors.
But, he also sent along a U.S. map that had been colored
to show that none of the same four colors had to be used for
adjacent states.
(To enter the March Math Mania contest, just click
here.)
Here are the correct answers for the February Math Mania
contest:
February Math Mania Solutions
1. Continue the sequence.
4 25
64
121 196
289
?
2. Find the most recent year that reads the
same upside down as right side up. For example, 1881 reads
the same if you turn your paper upside down.
Answer: 1961
3. In how many different ways can you receive
$20 (U.S. currency) from your bank if you ask for paper money
only? Assume that the bank has no $2 bills.
Answer: 10. I suggest that you make an
organized list so you don't forget anything.
1 way using a twenty-dollar bill:
$20
4 ways using at least one ten-dollar
bill:
$10, $10
$10, $5, $5
$10, $5, $1, $1, $1, $1, $1
$10, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1
4 ways using at least one five-dollar
bill, but no larger bills:
$5, $5, $5, $5
$5, $5, $5, $1, $1, $1, $1, $1
$5, $5, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1
$5, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1,
$1, $1
1 way using all one-dollar
bills:
$1, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1, $1,
etc…
4. What is the fewest number of colors you
can use to color a map of the United States without using
the same color on any adjacent states? In other words, two
or more states of the same color may not touch.
Answer: 4. In fact, four
colors are the most needed for any map-real or imaginary.
Create your own map and test it out!
5. Insert +, -, x, and/or ( ) between the
numbers to make a true equation. Don't forget order of operations!
Answer: 1 - 2 + 3 + 4 + 5 x 6 + 7 + 8
+ 9 = 60
Perform multiplication first, then addition and subtraction
from left to right.
Other solutions may exist,
as with many problems of this nature.
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=4,
5