Simplify the following text for a Grade 3 native English-speaking person.
Original: With a mass of 15.55 grams and a diameter of 31.51 mm , the Australian 50-cent coin is one of the largest sized coins used in the world today .
Simplified: The Australian 50-cent coin is a large coin . It weighs 15.55 grams and is 31.51 mm across .