Which of the following variables contain numbers?

var pi = 3.141592653589793;var height = 1.72;var age = "42";var radius;

Right on! Integers and floats are numbers. If a number is in quotes, it's a string and if a variable doesn't have a value, it's undefined.

Yikes! Integers and floats are numbers. If a number is in quotes, it's a string and if a variable doesn't have a value, it's undefined.