Variable creation and assignment in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign the value 10 to the variable x.

MATLAB

x = [1];

Drag options to blanks, or click blank then click option'

A'10'

Bx

C10

Dten

Attempts:

3 left

💡 Hint

Common Mistakes

Putting the number 10 inside quotes, which makes it a string.

Using a variable name instead of a value.

In MATLAB, to assign a numeric value to a variable, just write the number without quotes.

2fill in blank

medium

Complete the code to assign the string 'hello' to the variable greeting.

MATLAB

greeting = [1];

Drag options to blanks, or click blank then click option'

Ahello

B'hello'

C"hello"

Dgreeting

Attempts:

3 left

💡 Hint

Common Mistakes

Using double quotes instead of single quotes for strings.

Not using quotes at all.

In MATLAB, strings are enclosed in single quotes.

3fill in blank

hard

Fix the error in the code to assign the value 5 to variable num.

MATLAB

num = [1];

Drag options to blanks, or click blank then click option'

A'5';

B5

Cnum;

D5;

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the semicolon at the end of the statement.

Putting the number inside quotes.

In MATLAB, each statement must end with a semicolon to suppress output.

4fill in blank

hard

Fill both blanks to create a variable 'result' that stores the sum of 3 and 7.

MATLAB

result = [1] [2] 7;

Drag options to blanks, or click blank then click option'

A3

B+

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

Swapping the order of numbers and operators.

To add 3 and 7, use the plus sign (+) between them.

5fill in blank

hard

Fill all three blanks to create a variable 'area' that stores the product of length and width.

MATLAB

area = [1] [2] [3];

Drag options to blanks, or click blank then click option'

Alength

B*

Cwidth

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of multiplication.

Mixing up variable names.

To calculate area, multiply length by width using the * operator.

Practice

1.

What does the following MATLAB code do?
x = 10;

easy

A. Creates a variable named x and assigns it the value 10

B. Creates a function named x with input 10

C. Deletes the variable x

D. Prints the number 10 on the screen

Solution

1. Step 1: Understand variable assignment syntax

   The code uses = to assign a value to a variable.

2. Step 2: Identify the variable and value

   Variable x is assigned the value 10.

3. Final Answer:

   Creates a variable named x and assigns it the value 10 -> Option A

4. Quick Check:

   Variable assignment = Creates variable with value [OK]

Hint: Look for '=' to spot variable assignment [OK]

Common Mistakes:

• Thinking '=' prints output
• Confusing variable creation with function definition
• Missing semicolon means output prints but variable still created

2.

Which of the following is the correct way to assign the value 5 to variable a in MATLAB?

easy

A. a == 5;

B. a = 5;

C. 5 = a;

D. a := 5;

Solution

1. Step 1: Recall MATLAB assignment operator

   MATLAB uses = to assign values to variables.

2. Step 2: Check each option

   a = 5; uses a = 5; which is correct syntax.

3. Final Answer:

   a = 5; -> Option B

4. Quick Check:

   Assignment uses '=' in MATLAB [OK]

Hint: Use single '=' for assignment, not '==' [OK]

Common Mistakes:

• Using '==' which is a comparison, not assignment
• Trying to assign value to a number (5 = a)
• Using ':=' which is not MATLAB syntax

3.

What is the value of variable y after running this code?

y = 3;
y = y + 4;

medium

A. 7

B. 3

C. 4

D. Error

Solution

1. Step 1: Assign initial value to y

   Variable y is first set to 3.

2. Step 2: Add 4 to current value of y

   New value is 3 + 4 = 7.

3. Final Answer:

   7 -> Option A

4. Quick Check:

   3 + 4 = 7 [OK]

Hint: Add numbers step-by-step to find final value [OK]

Common Mistakes:

• Thinking y stays 3 after addition
• Confusing assignment with comparison
• Expecting syntax error due to reuse of variable

4.

Identify the error in this MATLAB code:

1var = 10;

medium

A. Variable names cannot contain letters

B. Missing semicolon at the end

C. Assignment operator is wrong

D. Variable names cannot start with a number

Solution

1. Step 1: Check variable naming rules

   MATLAB variable names must start with a letter, not a number.

2. Step 2: Analyze given variable name

   Variable name 1var starts with '1', which is invalid.

3. Final Answer:

   Variable names cannot start with a number -> Option D

4. Quick Check:

   Variable names start with letters [OK]

Hint: Variable names must start with a letter [OK]

Common Mistakes:

• Thinking semicolon is mandatory for syntax
• Confusing assignment operator '=' with '=='
• Assuming numbers can start variable names

5.

You want to create two variables a and b where a is 5 and b is twice a. Which code correctly does this?

a = 5;
b = 2 * a;

hard

A. a = 5;b = a * a;

B. a = 5;b = 2 + a;

C. a = 5;b = 2 * a;

D. a = 5;b = a / 2;

Solution

1. Step 1: Assign value 5 to variable a

   Code a = 5; correctly assigns 5 to a.

2. Step 2: Assign b as twice a

   Code b = 2 * a; correctly calculates twice the value of a.

3. Final Answer:

   a = 5; b = 2 * a; -> Option C

4. Quick Check:

   b = 2 * a means b is double a [OK]

Hint: Multiply variable by 2 to get double value [OK]

Common Mistakes:

• Adding instead of multiplying for double
• Dividing instead of multiplying
• Multiplying variable by itself instead of 2