Answers

Challenge 4-6/Ages 9-11

Award

Presented to MathWorld Interactive by Nomads #1 of Pond Creek, Oklahoma

We can make secret codes by letting numbers represent letters of the alphabet.  We can assign the following values:

Vowels:  A=6, E=8, I=4,O=2, U=10, *=0(zero)

Consonants:  B=1, C=3, D=5, F=7, G=9, H=11, J=13, K=15, L=17, M=19, N=21, P=23, Q=25, R=27, S=29, T=31, V=33, W=35, X=37, Z=41.

To code the word "cat," we find the numbers for each letter.  CAT is 3-6-31.

We can decode words.

Coding can be a great way to send secret messages.

There are two kinds of letters, vowels and consonants.  The vowels are coded with even numbers and the consonants are coded with odd numbers.

We can change the way we code messages by adding 2 to the consonant numbers and subtracting 2 from the vowel numbers.

We can code messages with formulas and then change to the letters that come out.

2.  We are trying to decode the messages and see what they say.

3.  I read the different decoding strategies and applied them to the problems.

4.  Solutions:

Exercise I

A) 29-23-2-2-21; 19-6-31-11; 3-2-19-23-10-31-8-27

B)  PEN; ERASER; SECRET

Exercise II

A)  21-4-33-13-2-31-9-8-23; 2-19-*-35-6-33-*-19-6-4-29-23; 5-*-25-8-33-6-5-*-*-19

B)  BANANA; YOU DID IT; CALL THE NOLICE (Did you do that on purpose?  Isn't it supposed to be "call the police?)

C)  D*FI X*SF; AMAQJIPVTPAWAS G*SHAV

This can't be done using the code the way that it's written because the "Z" wouldn't have any letter assigned to it.  To make it work, I pretended the alphabet was a cirlce, so the "Z" would come back to be a "B."  So the decoded message would look like:

BACSIT ISA OP VJA B**

MESSAGE MEET ME

5.  I checked my work by going through and making sure I had all my solutions correct.  I checked the one about "call the Nolice" about six times.  I still think I'm right!

6.  msiht asi tym hartx e ieghellahc srof fuoy uot nedoced

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