Arithmetic operators in Javascript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add two numbers and store the result in sum.

Javascript

let a = 5;
let b = 3;
let sum = a [1] b;

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

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using - instead of + will subtract instead of add.

The + operator adds two numbers together.

2fill in blank

medium

Complete the code to multiply two numbers and store the result in product.

Javascript

let x = 4;
let y = 7;
let product = x [1] y;

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

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using + will add instead of multiply.

The * operator multiplies two numbers.

3fill in blank

hard

Fix the error in the code to correctly divide num1 by num2.

Javascript

let num1 = 20;
let num2 = 4;
let result = num1 [1] num2;

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

A+

B/

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using * multiplies instead of divides.

The / operator divides the first number by the second.

4fill in blank

hard

Fill both blanks to create an object that maps numbers to their squares only if the number is even.

Javascript

const squares = {n[1]2 for n in [1, 2, 3, 4, 5, 6] if n [2] 2 === 0};

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

A**

B%

C===

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of ** will add instead of square.

The ** operator raises a number to a power (square here). The % operator finds the remainder, used to check if a number is even.

5fill in blank

hard

Fill all three blanks to create an object mapping uppercase letters to their ASCII codes only if the code is greater than 65.

Javascript

const codes = {[[1]]: [2] for [3] of ['A', 'B', 'C', 'D'] if [2] > 65};

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

Aletter

Bletter.charCodeAt(0)

Dcode

Attempts:

3 left

💡 Hint

Common Mistakes

Using for ... in instead of for ... of will iterate keys, not values.

letter is the variable for each character. charCodeAt(0) gets the ASCII code. The loop uses for ... of to iterate over letters.

Practice

1. Which arithmetic operator in JavaScript is used to find the remainder of a division?

easy

A. %

B. /

C. **

D. *

Solution

1. Step 1: Understand the remainder operator

   The operator % returns the remainder after division of two numbers.

2. Step 2: Compare with other operators

   / is division, ** is power, and * is multiplication, so they don't give remainder.

3. Final Answer:

   % -> Option A

4. Quick Check:

   Remainder operator = % [OK]

Hint: Remainder operator looks like a percent sign % [OK]

Common Mistakes:

• Confusing division / with remainder %
• Using * or ** instead of %
• Thinking + or - can give remainder

2. Which of the following is the correct syntax to calculate 5 to the power of 3 in JavaScript?

easy

A. 5 ** 3

B. 5 ^^ 3

C. 5 ^ 3

D. pow(5, 3)

Solution

1. Step 1: Identify the power operator in JavaScript

   JavaScript uses ** to calculate powers, like 5 ** 3 means 5 to the power 3.

2. Step 2: Check other options for correctness

   ^ is bitwise XOR, ^^ is invalid syntax, and pow() is not a built-in function in JavaScript.

3. Final Answer:

   5 ** 3 -> Option A

4. Quick Check:

   Power operator = ** [OK]

Hint: Use ** for power, not ^ or pow() [OK]

Common Mistakes:

• Using ^ instead of ** for power
• Trying to use pow() like in other languages
• Typing invalid operators like ^^

3. What will be the output of the following code?

console.log(10 % 4);

medium

A. 6

B. 0

C. 2

D. 4

Solution

1. Step 1: Calculate 10 divided by 4

   10 divided by 4 is 2 with a remainder of 2.

2. Step 2: Understand the % operator

   The % operator returns the remainder, so 10 % 4 equals 2.

3. Final Answer:

   2 -> Option C

4. Quick Check:

   10 % 4 = 2 [OK]

Hint: Remainder is what's left after division [OK]

Common Mistakes:

• Confusing remainder with quotient
• Thinking % does division
• Choosing 0 or 4 as remainder incorrectly

4. Find the error in this code snippet:

let result = 5 **;
console.log(result);

medium

A. console.log syntax error

B. Using wrong operator for power

C. Variable name 'result' is invalid

D. Missing right operand for ** operator

Solution

1. Step 1: Check the power operator usage

   The power operator ** needs two operands, like 5 ** 2. Here, the right operand is missing.

2. Step 2: Verify other parts of the code

   The variable name and console.log syntax are correct, so no errors there.

3. Final Answer:

   Missing right operand for ** operator -> Option D

4. Quick Check:

   Power operator needs two numbers [OK]

Hint: Power operator needs number on both sides [OK]

Common Mistakes:

• Leaving out the second number after **
• Thinking variable names cause error here
• Assuming console.log is wrong

5. You want to split 100 candies equally among 6 kids and find how many candies remain undistributed. Which expression gives the number of leftover candies?

hard

A. 100 / 6

B. 100 % 6

C. 100 - 6

D. 100 ** 6

Solution

1. Step 1: Understand the problem

   We want the leftover candies after dividing 100 by 6, which means the remainder.

2. Step 2: Choose the correct operator

   The remainder operator % gives the leftover amount, so 100 % 6 is correct.

3. Final Answer:

   100 % 6 -> Option B

4. Quick Check:

   Leftover = total % number [OK]

Hint: Use % to find leftovers after division [OK]

Common Mistakes:

• Using / which gives quotient, not remainder
• Subtracting numbers directly instead of remainder
• Using power operator mistakenly