Number literal formats (underscore, hex, binary) in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of using underscores in Kotlin number literals?

Underscores in Kotlin number literals make large numbers easier to read by visually separating digits, like commas in regular numbers. They do not affect the actual value.

beginner

How do you write a hexadecimal number literal in Kotlin?

In Kotlin, a hexadecimal number literal starts with 0x or 0X followed by digits 0-9 and letters A-F (case insensitive). For example, 0x1A3F.

beginner

How do you write a binary number literal in Kotlin?

A binary number literal in Kotlin starts with 0b or 0B followed by only 0s and 1s. For example, 0b1010_1101.

intermediate

Can underscores be placed anywhere in Kotlin number literals?

Underscores can be placed between digits in Kotlin number literals to improve readability, but not at the start or end of the number, nor next to the decimal point or prefixes like 0x or 0b.

intermediate

Example: What is the decimal value of 0xFF_EC_DE_5E in Kotlin?

The hexadecimal literal 0xFF_EC_DE_5E equals 4293713502 in decimal. The underscores are ignored when computing the value.

Which of the following is a valid Kotlin binary literal?

A 0b1021

B 0x1010_1101

C 1010_1101b

D 0b1010_1101

Binary literals start with 0b or 0B and contain only 0s and 1s. Option D is correct.

What does the underscore do in Kotlin number literals?

A Marks the number as hexadecimal

B Multiplies the number by 1000

C Separates digits for readability without changing the value

D Indicates a negative number

Underscores improve readability but do not affect the number's value.

Which prefix is used for hexadecimal literals in Kotlin?

A 0x

B #

C 0b

D 0h

Hexadecimal literals start with 0x or 0X.

Is this Kotlin number literal valid? 0x_1A3F

A No, underscore cannot be right after the prefix

B Yes, underscores can be anywhere

C Yes, but only in binary literals

D No, underscores are not allowed in hex literals

Underscores cannot be placed immediately after the prefix like 0x.

What is the decimal value of 0b1111_0000?

A 15

B 240

C 11110000

D 128

Binary 11110000 equals decimal 240.

Explain how to write and use underscores in Kotlin number literals.

Think about how commas help read big numbers.

Describe how to write hexadecimal and binary number literals in Kotlin with examples.

Remember the prefixes and allowed digits.