Who is asking: Parent
What is a group of three numbers called in a large number?
My son has this question on his 4th grade worksheet. I've taught middle school math for 7 years and nver heard of it.
I INTERPRET the question as follows:
for numbers over 9999, the digits are grouped into sets of three (and
separated by commas or spaces) - this is sometimes referred to as
periodicity, or period, or period value (although I only know this because
I looked the term up in a math dictionary from 1933 just to make sure I
for example, in the number 123,456,789
Period is like place value except for place value we look at individual
digits (e.g., the 5 in the above number is in the 10 thousands column and
represents 5 ten thousands or 50 thousand), whereas period looks at 3
digits in a group.
Period is the concept needed to properly name numbers over 9999.
I hope this is the interpretation your teacher was looking for.
- 789 is the 1st period and is units (i.e. seven hundred and eighty nine UNITS)
- 456 is the 2nd period and is thousands (i.e. four hundred and fifty six
- 123 is the 3rd period and is millions (i.e. one hundred and twenty three