Representing text with number codes

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. How does a computer store the letter B?

A As a number code

B As a tiny picture of the letter

2. In a simple A=1 code, which number stands for the letter C?

A 3

B 4

3. In an A=1 code, the numbers 8 and 9 stand for which word?

A HI

B IH

4. Which statement about character codes is true?

A Only letters have codes, so symbols like ! do not

B Every letter and symbol has its own number code

5. What does the computer do with a character code when it shows text on the screen?

A It shows the number instead of the character

B It turns the number back into the character

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1A=1, B=2, C=3		AThe word HI written as number codes, with H as 8 and I as 9
2HI = 8 9		BA simple code where each letter is stored as its place in the alphabet
3A computer stores the letter C as a number, then turns it back into a letter on screen		CThe computer stores B as the number 2, not as a letter. The number is turned back into B when it is shown.
4A secret code swaps each letter for its number so others cannot read the message at a glance		DC = 3
5In an A=1 code, D = 5		ED is the 4th letter, so it should be 4. The number 5 is the code for E.
6The computer stores the letter B as the letter 2		F3 1 20 = CAT

Definitions

character code

Fill in the Blanks

Complete each line of code by filling in the missing parts.

A = 1, B = 2, C = _

Code for CAB: 3, 1, _

A number for a letter is a _________ code

Stored number: 2 Shown on screen: _

Secret code for DOG: D=4, O=15, G=_

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A A = 1

B B = 2

C C = 4

D CAB is 3 1 2

Question 2

A word = CAB

B C becomes 3

C B becomes 2

D A becomes 2

E coded message: 3 1 2

Question 3

A In an A=1 code, A is 0

B B is 2

C C is 3

Question 4

A message: 8 9

B 8 is H

C 9 is J

D so the message says HI

Question 5

A letter = 'A'

B code = chr(letter)

C print(code)

D # prints 65

Answer Key

Representing text with number codes

Section A: Quick Questions

A — As a number code

A — 3

A — HI

B — Every letter and symbol has its own number code

B — It turns the number back into the character

Section B: Match the Pairs

A=1, B=2, C=3 → A simple code where each letter is stored as its place in the alphabet

HI = 8 9 → The word HI written as number codes, with H as 8 and I as 9

A computer stores the letter C as a number, then turns it back into a letter on screen → C = 3

A secret code swaps each letter for its number so others cannot read the message at a glance → 3 1 20 = CAT

In an A=1 code, D = 5 → D is the 4th letter, so it should be 4. The number 5 is the code for E.

The computer stores the letter B as the letter 2 → The computer stores B as the number 2, not as a letter. The number is turned back into B when it is shown.

Section C: Definitions

character code — A number the computer uses to stand for one letter or symbol. It stores the number, then turns it back into the character on screen. In one A=1 code, A is 1 and B is 2.

Section D: Fill in the Blanks

A = 1, B = 2, C = 3

Code for CAB: 3, 1, 2

A number for a letter is a character code

Stored number: 2
Shown on screen: B

Secret code for DOG: D=4, O=15, G=7

Section E: Spot the Error

C — In an A=1 code, C is the third letter, so C = 3, not 4.

D — In an A=1 code, A is the first letter, so A becomes 1. The number 2 is the code for B.

A — In an A=1 code, A is 1. Because B is 2 and C is 3, A cannot be 0.

C — In an A=1 code, 9 is the letter I (A=1 ... H=8, I=9). J would be 10. The message says HI, so 9 must be I.

B — ord() changes a letter into its number code. chr() changes a number into a letter. The line should be code = ord(letter).