Arithmetic Operators in Dart

Introduction

Arithmetic operators allow you to perform mathematical calculations on numeric values. Dart supports all standard arithmetic operators you would expect from a modern programming language.

Why It Matters

Every program that deals with numbers — from calculators to games to financial apps — relies on arithmetic operators. Understanding them is a fundamental building block of programming logic.

Arithmetic Operators

Code Example

void main() {
  int a = 20;
  int b = 6;

  print(a + b);   // 26
  print(a - b);   // 14
  print(a * b);   // 120
  print(a / b);   // 3.3333333333333335
  print(a ~/ b);  // 3  (integer division, no decimal)
  print(a % b);   // 2  (remainder of 20 / 6)
  print(-a);      // -20

  // Increment and decrement
  int count = 5;
  count++;
  print(count);   // 6
  count--;
  print(count);   // 5

  // Combined with doubles
  double price = 19.99;
  double tax = price * 0.1;
  print(price + tax); // 21.989
}

26
14
120
3.3333333333333335
3
2
-20
6
5
21.989

Explanation

• + adds two numbers together.
• - subtracts the right operand from the left.
• * multiplies two numbers.
• / always returns a double, even if the result is a whole number.
• ~/ returns only the integer part of division (truncates the decimal).
• % returns the remainder after integer division — very useful for checking even/odd numbers.
• ++ and -- increment or decrement a variable by 1.

Notes

• In Dart, 10 / 2 returns 5.0 (a double), not 5 (an int). Use ~/ if you need an integer result.
• The ++ operator can be prefix (++x) or postfix (x++). Prefix increments before use; postfix increments after use.
• Dividing by zero with / on doubles produces Infinity; dividing integers with ~/ throws an exception.

Common Mistakes

• Using / when you need an integer result — use ~/ instead.
• Forgetting that int + double produces a double in Dart.
• Confusing % (modulo) with percentage — 10 % 3 is 1, not 0.1.

Summary

Dart's arithmetic operators cover addition (+), subtraction (-), multiplication (*), division (/), integer division (~/), and modulo (%). Remember that / always returns a double. Use ~/ when you need a whole-number result and % to find remainders.