************************************ MathMagic Cycle 4: Level 4-6 Regular ************************************ CODING and DECODING You can make secret codes by letting numbers represent letters of the alphabet. We can let: 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, Y=39, Z=41 CODING So, to Code the word CAT, we find the numbers for each letter. Look up C. Its C=3. Look up A. Its A=6. Look up T. Its T=31. So, CAT is 3 6 31. DECODING Now lets Decode a word and see what we get. Decode 5 2 9: What is 5? 5=D. What is 2? 2=O. What is 9? 9=G. So, 5 2 9 is DOG! EXERCISE I A) Code each below: SPOON MATH COMPUTER B) Decode each below: 23 8 21 8 27 6 29 8 27 29 8 3 27 8 31 C) Code the name of your school. As you can see, if you have the decoder, coder can be a great way to send secret messages. Now, notice there are two kinds of letters, vowels (a e i o u) and consonants (all the rest). Notice that the vowels are coded with even numbers and consonants are coded with odd numbers. So, VOWELS=EVEN, and CONSONANTS=ODD. We can make our code better. Lets make: VOWELS = EVEN - 2, and CONSONANTS = ODD + 2 Now to Code CAT: C is a consonant, so C = 3 + 2 = 5; A is a vowel, so A = 6 - 2 = 4; T is a consonant, so T = 31 + 2 = 33 So CAT is 5 4 33 Now, Decoding requires you to remove the code, and can be a little more involved. EXERCISE II A) Code the Messages below using our new code MATH IS FUN SAY HELLO TWENTY FOUR HOURS B) Decode the Messages below using our new code 3 4 23 4 23 4 41 0 8 7 2 7 2 33! 5 4 19 19 33 13 6 23 0 19 2 5 6 Finally, we can really soup up our code by coding our message with our formulas, and then changing to the letters that come out. So CAT becomes C = 3 + 2 = 5 = D A = 6 - 2 = 4= I T = 31 + 2 = 33 = V So CAT is now DIV in our new code. EXERCISE III A) Code these messages into a new word message. CODE WORD ELEPHANTS NEVER FORGET ZEBRAS ARE IN THE ZOO (can this be done?--if not, what can be done so that the code will be worked) B) Decode these messages into readable messages NATTIHA NAAV NA OP QISOT UJA GOMA OT V*Q TADSAV **************************