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Arithmetic operators

Learn arithmetic with +, -, *, / and %.

Arithmetic operators

In Kotlin there are five basic arithmetic operators: + (addition), - (subtraction), * (multiplication), / (division) and % (modulo).

Integer division yields an integer: 7 / 2 → 3. Modulo yields the remainder: 7 % 2 → 1.

val a = 10
val b = 3
println(a + b)   // 13
println(a - b)   // 7
println(a * b)   // 30
println(a / b)   // 3
println(a % b)   // 1

Practice Try arithmetic

Write a fun main(). Declare val a = 10 and val b = 3. Print the remainder with println(a % b).

Sample solution

Main.kt
fun main() {
    val a = 10
    val b = 3
    println(a % b)
}

Expected output

1

Integer division

In Kotlin the division of two Ints yields an Int; so 7 / 2 → 3 (not 3.5). For a decimal result, at least one side must be Double: 7.0 / 2 → 3.5 or 7 / 2.0 → 3.5.

This behavior is a common pitfall when integer division does not yield the expected result. Make both sides Double for consistency.

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What does `7 % 2` return?

  • 0
  • 3
  • 3.5
  • 1 Correct answer

Explanation: The remainder of 7 divided by 2 is 1.

2 Arithmetic operators: fill in the missing part

Question 
val remainder = 7 ____ 2
println(remainder)  // 1
Answer 
val remainder = 7 % 2
println(remainder)  // 1

Explanation: The % operator yields the remainder.

3 Arithmetic operators: match the terms

Term Meaning
+ Addition
- Subtraction
* Multiplication
% Modulo

All lessons in Beginner

1 Kotlin basics

  1. What is Kotlin?
  2. Your first program
  3. The main function
  4. Comments
  5. String templates
  6. Summary - Kotlin basics

2 Variables

  1. val and var
  2. Type inference
  3. const
  4. lateinit
  5. by lazy
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. Boolean and Char
  4. String
  5. Any and Unit
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Elvis operator
  6. Summary - Operators

6 Strings

  1. Creating strings
  2. String templates
  3. String methods
  4. substring
  5. split and replace
  6. Summary - Strings

7 Conditionals

  1. The if statement
  2. else and else if
  3. if expression
  4. when
  5. when expression
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. Range
  5. break and continue
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Creating arrays
  2. Array access
  3. Array size
  4. Array loop
  5. Array methods
  6. Summary - Arrays

11 Lists

  1. Creating lists
  2. List operations
  3. List access
  4. List iteration
  5. List methods
  6. Summary - Lists

12 Maps and Sets

  1. Creating sets
  2. Set operations
  3. Creating maps
  4. Map operations
  5. Map iteration
  6. Summary - Maps and Sets

13 Functions

  1. Defining functions
  2. Return values
  3. Expression body
  4. Default parameters
  5. Named arguments
  6. Summary - Functions

14 Null safety

  1. Nullable types
  2. ?, !! and ?:
  3. let
  4. Null check
  5. lateinit
  6. Summary - Null safety

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Advanced string operations

  1. Regex
  2. matches and find
  3. replace
  4. StringBuilder
  5. trim and pad
  6. Summary - Advanced strings

17 Enums

  1. enum class
  2. Enum values
  3. Enum properties
  4. when with enum
  5. Enum and range
  6. Summary - Enums

18 Exceptions

  1. try/catch
  2. throw
  3. finally
  4. try expression
  5. Custom exceptions
  6. Summary - Exceptions

19 Class basics

  1. class
  2. Constructor
  3. Properties
  4. Methods
  5. this
  6. Summary - Class basics

20 Beginner final

  1. Project design
  2. Classes
  3. Collections
  4. Error handling
  5. Putting it together