Variables and data storage in Intro to Computing - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ trace

intermediate

Trace the value of variable after assignments

Consider the following steps where a variable is assigned new values. What is the final value of x after all steps?

Intro to Computing

x = 5
x = x + 3
x = x * 2
x = x - 4

A 12

B 16

C 10

D 8

💡 Hint

Calculate step by step: start with 5, add 3, then multiply by 2, then subtract 4.

Start with x = 5. Then x + 3 = 8. Next multiply by 2: 8 * 2 = 16. Finally subtract 4: 16 - 4 = 12. So the final value is 12.

🧠 Conceptual

intermediate

Identify the correct description of variable storage

Which option best describes what happens when a variable stores a value in a computer?

A The variable changes the value into a picture.

B The variable sends the value to the screen immediately.

C The variable deletes the value after storing it.

D The variable creates a box in memory that holds the value.

💡 Hint

Think about how a variable keeps information for later use.

A variable acts like a labeled box in the computer's memory where a value is kept until needed. It does not send the value to the screen or delete it immediately.

❓ Comparison

advanced

Compare variable types and their storage sizes

Which option correctly orders these variable types from smallest to largest typical storage size?

A Integer, Boolean, String, Floating-point

B String, Boolean, Integer, Floating-point

C Boolean, Integer, Floating-point, String

D Floating-point, Integer, Boolean, String

💡 Hint

Think about how much space each type usually needs in memory.

Booleans usually need 1 bit or byte, integers need more bytes, floating-point numbers need even more, and strings can vary but often require the most space.

❓ identification

advanced

Identify the error in variable naming

Which variable name is invalid in most programming languages?

A user_name

B 2ndPlace

C _tempValue

D totalScore

💡 Hint

Variable names usually cannot start with a number.

Variable names cannot start with digits. Option B starts with '2', which is invalid. Other options start with letters or underscore, which are allowed.

🚀 Application

expert

Determine the output after variable swapping

Given the code below, what is the value of a and b after execution?

Intro to Computing

a = 10
b = 20
a, b = b, a

A a = 20, b = 10

B a = 10, b = 20

C a = 30, b = 0

D a = 20, b = 20

💡 Hint

Look at how the values are swapped in one line.

The line a, b = b, a swaps the values of a and b. So a becomes 20 and b becomes 10.