Operator precedence in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate the correct result using operator precedence.

MATLAB

result = 3 + 4 * [1];

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

A2

B5

C1

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Adding before multiplying, which changes the result.

Ignoring operator precedence and calculating left to right.

Multiplication (*) has higher precedence than addition (+), so 4 * 2 is calculated first, then 3 is added.

2fill in blank

medium

Complete the code to correctly compute the expression with parentheses affecting precedence.

MATLAB

result = (3 + 4) * [1];

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

A1

B5

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Multiplying before adding despite parentheses.

Ignoring parentheses and calculating left to right.

Parentheses change the order: 3 + 4 is calculated first, then multiplied by 2.

3fill in blank

hard

Fix the error in the expression to get the correct result considering operator precedence.

MATLAB

result = 10 - 4 / [1] + 2;

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

A2

B5

C4

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Performing subtraction before division.

Ignoring operator precedence and calculating left to right.

Division has higher precedence, so 4 / 3 is calculated first, then subtraction and addition follow left to right.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that uses operator precedence correctly.

MATLAB

result = containers.Map([1], [2]);

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

A{'a', 'b', 'c'}

B[1, 2, 3]

C[3, 4, 5]

D{'x', 'y', 'z'}

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets for keys instead of curly braces.

Mixing types between keys and values.

The keys must be a cell array of strings, and the values a numeric array. This matches MATLAB's containers.Map syntax.

5fill in blank

hard

Fill all three blanks to correctly compute a complex expression respecting operator precedence.

MATLAB

result = ([1] + [2]) * [3];

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

A5

B3

C2

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Multiplying before adding.

Ignoring parentheses.

Parentheses force addition of 3 and 4 first, then multiply by 2.

Practice

1. In MATLAB, which operator has the highest precedence in the expression 3 + 4 * 2?

easy

A. Subtraction (-)

B. Addition (+)

C. Division (/)

D. Multiplication (*)

Solution

1. Step 1: Recall operator precedence rules

   Multiplication and division have higher precedence than addition and subtraction in MATLAB.

2. Step 2: Apply precedence to the expression

   In 3 + 4 * 2, multiplication happens first, so 4 * 2 = 8, then addition: 3 + 8 = 11.

3. Final Answer:

   Multiplication (*) -> Option D

4. Quick Check:

   Multiplication before addition = Multiplication (*) [OK]

Hint: Multiply/divide before add/subtract unless parentheses used [OK]

Common Mistakes:

• Adding before multiplying
• Ignoring operator precedence
• Assuming left-to-right always applies

2. Which of the following MATLAB expressions correctly uses parentheses to ensure addition happens before multiplication?

easy

A. 3 + (4 * 2)

B. 3 + 4 * 2

C. (3 + 4) * 2

D. 3 * 4 + 2

Solution

1. Step 1: Understand parentheses effect

   Parentheses force MATLAB to calculate inside them first, overriding normal precedence.

2. Step 2: Check each expression

   Only (3 + 4) * 2 adds 3 and 4 first, then multiplies by 2.

3. Final Answer:

   (3 + 4) * 2 -> Option C

4. Quick Check:

   Parentheses change order = (3 + 4) * 2 [OK]

Hint: Use parentheses to change normal operator order [OK]

Common Mistakes:

• Ignoring parentheses effect
• Assuming multiplication always first
• Misplacing parentheses

3. What is the output of the following MATLAB code?

a = 5 + 3 * 2 / 6 - 1;

medium

A. 5.0

B. 6

C. 6.0

D. 5

Solution

1. Step 1: Calculate multiplication and division first

   Calculate 3 * 2 = 6, then 6 / 6 = 1.

2. Step 2: Perform addition and subtraction left to right

   Expression becomes 5 + 1 - 1, which is 5.0.

3. Final Answer:

   5.0 -> Option A

4. Quick Check:

   Multiply/divide first, then add/subtract = 5.0 [OK]

Hint: Multiply/divide before add/subtract, left to right [OK]

Common Mistakes:

• Adding before multiplying
• Ignoring division precedence
• Confusing integer and floating-point output

4. Identify the error in this MATLAB expression:

result = 4 + * 3;

medium

A. No error, valid expression

B. Syntax error due to misplaced operator

C. Runtime error due to undefined variable

D. Logical error in calculation

Solution

1. Step 1: Analyze the expression syntax

   The expression 4 + * 3 has two operators '+' and '*' without a number between them, which is invalid syntax.

2. Step 2: Confirm MATLAB error type

   MATLAB will throw a syntax error because the operator '*' cannot directly follow '+'.

3. Final Answer:

   Syntax error due to misplaced operator -> Option B

4. Quick Check:

   Operators must have operands between them [OK]

Hint: Check operators have numbers on both sides [OK]

Common Mistakes:

• Assuming expression is valid
• Ignoring operator placement rules
• Confusing syntax and runtime errors

5. Given the MATLAB expression:

value = 10 - 2 * (3 + 1) / 2 + 4;

What is the correct value of value after MATLAB evaluates it?

hard

A. 10

B. 8

C. 6

D. 12

Solution

1. Step 1: Calculate inside parentheses first

   (3 + 1) = 4.

2. Step 2: Perform multiplication and division next

   Calculate 2 * 4 = 8, then 8 / 2 = 4.

3. Step 3: Perform addition and subtraction left to right

   Expression becomes 10 - 4 + 4. Since + and - have same precedence and are left-associative: 10 - 4 = 6, then 6 + 4 = 10.

4. Final Answer:

   10 -> Option A

5. Quick Check:

   Parentheses, then multiply/divide, then add/subtract = 10 [OK]

Hint: Calculate parentheses first, then multiply/divide, then add/subtract [OK]

Common Mistakes:

• Adding before subtracting
• Ignoring parentheses
• Doing operations out of order