Numbers in Dart

Integer (int)

The int type stores whole numbers (positive, negative, or zero) without a decimal point. Dart integers can be arbitrarily large.

int a = 100;
int b = -50;
int hex = 0xFF;          // hexadecimal = 255
int binary = 0b1010;     // binary = 10 (Dart 3+)
print(a + b);            // 50
print(hex);              // 255

Double

The double type stores 64-bit floating-point numbers (numbers with decimals).

double pi = 3.14159;
double e = 2.71828;
double sci = 1.5e6;      // scientific notation = 1500000.0
print(pi.toStringAsFixed(2));  // 3.14

The num Type

num is the parent type of both int and double. Use it when a variable might hold either type:

num x = 10;     // int
x = 3.14;       // now double — allowed with num
print(x);       // 3.14

Parsing Numbers

Convert strings to numbers using int.parse() and double.parse():

String s1 = '42';
String s2 = '3.14';

int n1 = int.parse(s1);       // 42
double n2 = double.parse(s2); // 3.14

// Safe parsing (returns null on failure):
int? n3 = int.tryParse('abc'); // null
print(n3 ?? 0);                // 0

Math Operations

dart:math Library

import 'dart:math';

void main() {
  print(sqrt(16));       // 4.0
  print(pow(2, 8));      // 256.0
  print(max(10, 20));    // 20
  print(min(10, 20));    // 10
  print(pi);             // 3.141592653589793

  // Random number 0–99
  var random = Random();
  print(random.nextInt(100));
}

Example

void main() {
  double principal = 1000.0;
  double rate = 5.0;
  int years = 3;

  double interest = (principal * rate * years) / 100;
  double total = principal + interest;

  print('Principal: \$$${principal.toStringAsFixed(2)}');
  print('Interest: \$$${interest.toStringAsFixed(2)}');
  print('Total after $years years: \$$${total.toStringAsFixed(2)}');
}

Principal: $1000.00
Interest: $150.00
Total after 3 years: $1150.00

🧠 Quiz

Summary

Dart supports int for whole numbers and double for decimals. Use num when the type can be either. Parse strings with int.parse() or the safe int.tryParse(). Import dart:math for mathematical functions like sqrt(), pow(), and Random().