I didn’t find it clear but I think drew is correct. So I will use the clear sentence as I can to explain to drew that the statement is not clear so here it goes. A period has a group of three digits. Digits are separated into groups of three by commas which the standard form of a number refers to a type of notation. The notation is series or a written symbols used to represent certain amount and numbers in mathematics. The example of a period that has a group of three digits is 123,456,789 and will read as one hundred and twenty three million four hundred and fifty-six thousands seven hundred and eighty-nine.
