Arithmetic operators in Javascript - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of mixed arithmetic operations

What is the output of the following JavaScript code?

Javascript

const result = 10 + 5 * 2 - 8 / 4;
console.log(result);

A 16

B 24

C 18

D 20

💡 Hint

Remember the order of operations: multiplication and division happen before addition and subtraction.

Multiplication and division are done first: 5 * 2 = 10, 8 / 4 = 2. Then addition and subtraction: 10 + 10 - 2 = 18.

❓ Predict Output

intermediate

Result of increment and decrement operators

What will be logged to the console after running this code?

Javascript

let x = 5;
console.log(x++ + ++x);

A 12

B 11

C 10

D 13

💡 Hint

Remember that x++ uses the value before increment, ++x increments before use.

x++ returns 5 then x becomes 6; ++x increments x to 7 then returns 7; sum is 5 + 7 = 12.

❓ Predict Output

advanced

Output with modulus and exponentiation

What is the output of this code snippet?

Javascript

const a = 7 % 3;
const b = 2 ** 3;
console.log(a + b);

A 9

B 11

C 10

D 8

💡 Hint

Calculate modulus and exponentiation separately, then add.

7 % 3 is 1 (remainder), 2 ** 3 is 8, sum is 1 + 8 = 9.

❓ Predict Output

advanced

Division and floating point precision

What will this code output?

Javascript

console.log(0.1 + 0.2 === 0.3);

A TypeError

B false

C true

D undefined

💡 Hint

Think about how computers handle decimal numbers.

Due to floating point precision, 0.1 + 0.2 is not exactly 0.3, so the comparison is false.

🧠 Conceptual

expert

Understanding operator precedence and associativity

Consider the expression: 4 + 3 * 2 ** 2 / 4 - 1. What is the final value?

A 8

B 7

C 9

D 6

💡 Hint

Remember the order: exponentiation, multiplication/division, addition/subtraction, and left-to-right associativity for same precedence.

2 ** 2 = 4; then 3 * 4 = 12; 12 / 4 = 3; then 4 + 3 = 7; finally 7 - 1 = 6.