Dart supports sever built in types. These are the most common of the types that represent a single value.

• int
• double
• num
• String
• bool

int

An int is a whole number (integer).

int one = 1;
int age = 45;
int year = 2020;
// an int can be negative
int balance = -45;

double

A double is a floating-point number, or a number with a decimal point.

double percent = .65;
double rating = 4.5;
// a double can be negative
double negativeNumber = -87.42;

num

num is a super class of both int and double. Which means you can use num when dealing with numbers that could be an integer or floating-point number. They're best used when you don't know which of the types will be used.

num sum;
// now sum has an int value
sum = 4 + 5;
// by adding a double, sum now refers to a double value
sum = sum + 5.5;