Writing a sequence in Cambridge pseudocode

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Quick Questions

Shade in the A or B circle for each question.

1. Which program is a sequence?

A INPUT Num, then IF Num > 5 THEN OUTPUT Num, then ENDIF

B INPUT Num, then Total <- Num * 2, then OUTPUT Total

2. A program takes a number, doubles it and shows the answer. What is the correct order?

A OUTPUT Answer, then Answer <- Num * 2, then INPUT Num

B INPUT Num, then Answer <- Num * 2, then OUTPUT Answer

3. Which line is the PROCESS step in an input-process-output sequence?

A Area <- Length * Width

B INPUT Length

4. What is OUTPUT Total after these lines run? Total <- 5 Total <- Total + 3

A 8

B 5

5. What happens if you swap these two lines? X <- 4 OUTPUT X

A X has no value when it is output, so the output is wrong or an error

B The output is still 4 because the order does not matter

Match the Pairs

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

Left column		Right column
1INPUT Price Total <- Price * 2 OUTPUT Total		AAssignment uses = instead of the arrow <-. It should be Score <- 10.
2Total <- Price * 2 INPUT Price OUTPUT Total		BOUTPUT comes before the assignment, so Total has no value when it is output. The two statements must be swapped.
3A sequence program starts by declaring its variables, then takes input, then outputs a result		CA <- 5 B <- A + 3 OUTPUT B
4A program with no selection or iteration is a pure sequence: every statement runs exactly once, in order		DA sequence of input, then process, then output: the statements run once each, in order, from top to bottom
5OUTPUT Total Total <- 4 + 6		EThe order is wrong: Price is used in the calculation before it has been given a value from INPUT
6DECLARE Score : INTEGER Score = 10 OUTPUT Score		FDECLARE Age : INTEGER INPUT Age OUTPUT Age + 1

Definitions

sequence

Fill in the Blanks

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

DECLARE Price : INTEGER _____ Price OUTPUT Price

INPUT Price Total ← Price _ 3 OUTPUT Total

Count _ 0 Count ← Count + 1 OUTPUT Count

_______ Name : STRING INPUT Name OUTPUT Name

INPUT Mins Secs ← Mins * 60 ______ Secs

Spot the Error

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

Question 1

A DECLARE Price : REAL

B DECLARE Qty : INTEGER

C INPUT Price

D Qty INPUT

E OUTPUT Price * Qty

Question 2

A DECLARE Age = INTEGER

B INPUT Age

C Age <- Age + 1

D OUTPUT Age

Question 3

A DECLARE Cost : REAL

B INPUT Cost

C OUTPUT "Cost: " Cost

Question 4

A DECLARE Total : INTEGER

B Total = 10 + 5

C Total <- Total * 2

D OUTPUT Total

Question 5

A DECLARE Num : INTEGER

B INPUT Num

C Num := Num * 2

D OUTPUT Num

Answer Key

Writing a sequence in Cambridge pseudocode

Section A: Quick Questions

B — INPUT Num, then Total <- Num * 2, then OUTPUT Total

B — INPUT Num, then Answer <- Num * 2, then OUTPUT Answer

A — Area <- Length * Width

A — 8

A — X has no value when it is output, so the output is wrong or an error

Section B: Match the Pairs

INPUT Price Total <- Price * 2 OUTPUT Total → A sequence of input, then process, then output: the statements run once each, in order, from top to bottom

Total <- Price * 2 INPUT Price OUTPUT Total → The order is wrong: Price is used in the calculation before it has been given a value from INPUT

A sequence program starts by declaring its variables, then takes input, then outputs a result → DECLARE Age : INTEGER INPUT Age OUTPUT Age + 1

A program with no selection or iteration is a pure sequence: every statement runs exactly once, in order → A <- 5 B <- A + 3 OUTPUT B

OUTPUT Total Total <- 4 + 6 → OUTPUT comes before the assignment, so Total has no value when it is output. The two statements must be swapped.

DECLARE Score : INTEGER Score = 10 OUTPUT Score → Assignment uses = instead of the arrow <-. It should be Score <- 10.

Section C: Definitions

sequence — A program made of statements like DECLARE, <-, INPUT and OUTPUT that run one after another from top to bottom, with no selection or iteration. Changing the order changes the result.

Section D: Fill in the Blanks

DECLARE Price : INTEGER
INPUT Price
OUTPUT Price

INPUT Price
Total ← Price * 3
OUTPUT Total

Count ← 0
Count ← Count + 1
OUTPUT Count

DECLARE Name : STRING
INPUT Name
OUTPUT Name

INPUT Mins
Secs ← Mins * 60
OUTPUT Secs

Section E: Spot the Error

D — The keyword INPUT must come first, followed by the variable name. The line should be INPUT Qty.

A — A DECLARE statement uses a colon between the identifier and the data type. It should be DECLARE Age : INTEGER.

C — Items in an OUTPUT statement must be separated by commas. It should be OUTPUT "Cost: ", Cost.

B — Assignment uses the arrow <-. The = sign is a comparison operator in Cambridge pseudocode. It should be Total <- 10 + 5.

C — Cambridge pseudocode assigns with <-, not :=. The line should be Num <- Num * 2.