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Arithmetic operators

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

Arithmetic operators

Dart has six basic arithmetic operators: + (addition), - (subtraction), * (multiplication), / (division), % (modulo/remainder) and ~/ (integer division).

/ always returns a double: 10 / 3 = 3.333.... If you want an integer result use ~/: 10 ~/ 3 = 3.

% gives the remainder of division: 10 % 3 = 1. It is often used for odd/even checks (x % 2) and in loops.

Using modulo (%)

The % operator gives the remainder of a division. For example 10 % 3 = 1 because 10 divided by 3 fits 3 times (9) and the remainder is 1.

Its most common use is odd/even checks: if x % 2 == 0 then x is even; if x % 2 == 1 it is odd.

It also helps in loops: to do something every third turn write if (i % 3 == 0). This is a handy way for periodic tasks.

Practice Three operations

Write print(10 + 5), print(10 - 3) and print(4 * 3) inside void main().

Starter code

main.dart
// Print three arithmetic operations

Sample solution

main.dart
void main() {
  print(10 + 5);
  print(10 - 3);
  print(4 * 3);
}

Expected output

15
7
12

Questions and answers

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

1 Modulo operator

Question 
int kalan = 10 ____ 3;
Answer 
int kalan = 10 % 3;

Explanation: % gives the remainder.

2 What is the result of 10 ~/ 3?

  • 3.33
  • Throws an error
  • 3 Correct answer
  • 4

Explanation: ~/ does integer division; it drops the fraction.

3 Match the operators

Term Meaning
+ Addition
- Subtraction
* Multiplication
/ Division (double)

All lessons in Beginner

1 Dart basics

  1. What is Dart?
  2. Your first program
  3. dart run
  4. Comments
  5. String interpolation
  6. Summary - Dart basics

2 Variables

  1. var and type
  2. final
  3. const
  4. late
  5. Null safety
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. bool and String
  4. Type inference
  5. dynamic
  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. Null-aware operators
  6. Summary - Operators

6 Strings

  1. Creating strings
  2. String interpolation
  3. length and methods
  4. substring
  5. contains and indexOf
  6. Summary - Strings

7 Conditionals

  1. The if statement
  2. else and else if
  3. switch
  4. Pattern matching
  5. Ternary
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. for-in
  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 Lists

  1. Creating lists
  2. List access
  3. add and remove
  4. length and contains
  5. List methods
  6. Summary - Lists

11 Sets and Maps

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

12 Functions

  1. Defining functions
  2. Return values
  3. Arrow functions
  4. Optional parameters
  5. First-class functions
  6. Summary - Functions

13 Null safety in depth

  1. Nullable types
  2. Null-aware operators
  3. The ! operator
  4. late
  5. Null check
  6. Summary - Null safety

14 Class basics

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

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. split and join
  2. replace
  3. trim and pad
  4. RegExp
  5. StringBuffer
  6. Summary - Advanced strings

17 Enums

  1. Defining enums
  2. Enum values
  3. Enhanced enums
  4. switch with enum
  5. Enum and patterns
  6. Summary - Enums

18 Exceptions

  1. try/catch
  2. throw
  3. finally
  4. The Exception class
  5. on clause
  6. Summary - Exceptions

19 Async basics

  1. Future
  2. async/await
  3. then
  4. Future.error
  5. Future.wait
  6. Summary - Async basics

20 Beginner final

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