Operator precedence in R Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

R Programming

result <- 3 + 4 * [1]

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

A2

B2L

C2.0

Attempts:

3 left

💡 Hint

Common Mistakes

Adding 3 + 4 first, then multiplying by 2.

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

2fill in blank

medium

Complete the code to get the correct logical result considering operator precedence.

R Programming

result <- TRUE | FALSE & [1]

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

AFALSE

BTRUE

CNA

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Evaluating OR before AND, leading to wrong result.

AND (&) has higher precedence than OR (|), so FALSE & FALSE is evaluated first, resulting in FALSE, then TRUE | FALSE is TRUE.

3fill in blank

hard

Fix the error in the expression by completing the code with the correct operator.

R Programming

result <- (5 + 3) [1] 2 ^ 3

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

A/

B+

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using + or - instead of * changes the intended calculation.

Exponentiation (^) has higher precedence than multiplication (*), so 2 ^ 3 is calculated first, then multiplied by (5 + 3).

4fill in blank

hard

Fill both blanks to correctly calculate the expression considering operator precedence.

R Programming

result <- 10 [1] 4 [2] 2

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

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Doing addition or subtraction before division.

Multiplication and division have higher precedence than addition and subtraction. Here, 4 / 2 is calculated first, then added to 10.

5fill in blank

hard

Fill all three blanks to correctly compute the expression with proper operator precedence.

R Programming

result <- (8 [1] 2) [2] 3 [3] 4

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

A+

B*

C-

D^

Attempts:

3 left

💡 Hint

Common Mistakes

Ignoring parentheses or wrong operator order.

Parentheses are evaluated first: 8 + 2 = 10. Then multiplication and exponentiation follow. 3 ^ 4 is calculated first, then multiplied by 10.

Practice

1. In R, which operator has the highest precedence among these: +, *, ^, -?

easy

A. Subtraction (-)

B. Multiplication (*)

C. Addition (+)

D. Exponentiation (^)

Solution

1. Step 1: Recall operator precedence rules in R

   Exponentiation (^) has higher precedence than multiplication, addition, and subtraction.

2. Step 2: Compare given operators

   Among +, *, ^, and -, ^ is evaluated first.

3. Final Answer:

   Exponentiation (^) -> Option D

4. Quick Check:

   ^ > * > +, - [OK]

Hint: Remember: powers before multiply, multiply before add [OK]

Common Mistakes:

• Thinking multiplication is higher than exponentiation
• Confusing addition and subtraction precedence
• Ignoring operator precedence order

2. Which of the following R expressions is syntactically correct and respects operator precedence?

easy

A. 3 + 4 ** 2

B. 3 + 4 * 2

C. 3 + (4 * ) 2

D. 3 + * 4 2

Solution

1. Step 1: Check each expression for syntax correctness

   3 + 4 * 2 is a valid expression: addition and multiplication with correct syntax. Options A, B, and C have syntax errors.

2. Step 2: Confirm operator precedence in 3 + 4 * 2

   Multiplication happens before addition, so 4 * 2 is evaluated first, then added to 3.

3. Final Answer:

   3 + 4 * 2 -> Option B

4. Quick Check:

   Valid syntax and precedence respected [OK]

Hint: Check for valid operator placement and parentheses [OK]

Common Mistakes:

• Using invalid operators like ** in R
• Misplacing operators causing syntax errors
• Incorrect parentheses usage

3. What is the output of this R code?

result <- 2 + 3 * 4 ^ 2
print(result)

medium

A. 50

B. 74

C. 200

D. 100

Solution

1. Step 1: Evaluate exponentiation first

   4 ^ 2 equals 16.

2. Step 2: Multiply then add

   Multiply 3 by 16 to get 48, then add 2: 2 + 48 = 50.

3. Step 3: Confirm the calculation

   2 + 3 * 4 ^ 2 = 2 + 3 * 16 = 2 + 48 = 50.

4. Final Answer:

   50 -> Option A

5. Quick Check:

   ^ then * then + = 50 [OK]

Hint: Calculate powers first, then multiply, then add [OK]

Common Mistakes:

• Adding before multiplying
• Ignoring exponentiation precedence
• Misreading the expression order

4. Identify the error in this R expression:

value <- 5 + 2 * (3 - 1

medium

A. Missing closing parenthesis

B. Incorrect operator usage

C. Multiplication should be addition

D. No error, expression is correct

Solution

1. Step 1: Check parentheses balance

   The expression has an opening parenthesis after 2 * but no closing parenthesis.

2. Step 2: Confirm syntax error due to missing parenthesis

   R requires matching parentheses; missing one causes syntax error.

3. Final Answer:

   Missing closing parenthesis -> Option A

4. Quick Check:

   Parentheses must be balanced [OK]

Hint: Count opening and closing parentheses carefully [OK]

Common Mistakes:

• Ignoring missing parentheses
• Assuming operators are wrong instead
• Not checking syntax errors first

5. Given the vector v <- c(1, 2, 3), what is the result of this expression in R?

result <- 10 / 2 * v + 1

Choose the correct output.

hard

A. [1] 6 7 8

B. [1] 11 12 13

C. [1] 6 11 16

D. [1] 5 10 15

Solution

1. Step 1: Evaluate division and multiplication first

   10 / 2 equals 5, then multiply by vector v: 5 * c(1,2,3) = c(5,10,15).

2. Step 2: Add 1 to each element

   Add 1 to each element: c(5,10,15) + 1 = c(6,11,16).

3. Final Answer:

   [1] 6 11 16 -> Option C

4. Quick Check:

   Division and multiplication before addition [OK]

Hint: Do division and multiplication before addition on vectors [OK]

Common Mistakes:

• Adding 1 before multiplication
• Ignoring vectorized operations
• Misordering division and multiplication