Number literal formats (underscore, hex, binary) in Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Kotlin number literals with underscores

What is the output of this Kotlin code snippet?

Kotlin

fun main() {
    val number = 1_000_000
    println(number)
}

A 1000000

B 1000_000

C 1_000_000

D 100000

💡 Hint

Underscores in number literals are ignored by the compiler and only improve readability.

In Kotlin, underscores in numeric literals are just for readability and do not affect the actual value. So 1_000_000 is the same as 1000000.

❓ Predict Output

intermediate

Output of Kotlin hexadecimal literal

What will this Kotlin code print?

Kotlin

fun main() {
    val hexNumber = 0x1A
    println(hexNumber)
}

A 0x1A

B 1A

C 26

D 31

💡 Hint

Hexadecimal literals start with 0x and represent base 16 numbers.

0x1A in hexadecimal equals 26 in decimal, so the program prints 26.

❓ Predict Output

advanced

Output of Kotlin binary literal with underscores

What is the output of this Kotlin program?

Kotlin

fun main() {
    val binaryNumber = 0b1010_1101
    println(binaryNumber)
}

A 173

B 10101101

C 0b10101101

D 165

💡 Hint

Binary literals start with 0b and represent base 2 numbers. Underscores are ignored.

0b10101101 is binary for decimal 173, so the program prints 173.

❓ Predict Output

advanced

Sum of mixed number literals in Kotlin

What is the output of this Kotlin code?

Kotlin

fun main() {
    val a = 0xF
    val b = 0b10_10
    val c = 10_4
    println(a + b + c)
}

A 135

B 129

C 140

D 150

💡 Hint

Convert each literal to decimal before adding: 0xF = 15, 0b10_10 = 10, 10_4 = 104.

0xF is 15 decimal, 0b10_10 is binary 1010 which is 10 decimal, 10_4 is 104 decimal. Sum is 15 + 10 + 104 = 129.

❓ Predict Output

expert

Output of Kotlin code with invalid underscore placement

What error does this Kotlin code produce?

Kotlin

fun main() {
    val invalidNumber = 0x_1F
    println(invalidNumber)
}

A No error, prints 31

B NumberFormatException

C IllegalArgumentException

D SyntaxError

💡 Hint

Underscores cannot be placed right after the 0x prefix in hexadecimal literals.

Kotlin does not allow underscores immediately after the 0x prefix, so this code causes a syntax error.