digit - A symbol used to write numbers. The ten digits are 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9
expanded form - The representation of a number as a sum that shows the value of each digit    (536 is written as 500 + 30 + 6)
is equal to (=) - Having the same value. The = sign is used to show two numbers or expressions are equal. 
is greater than (>) - An inequality relationship showing that the number on the left of the symbol is greater than the number on the right (5 > 3)
is less than (<) - An inequality relationship showing that the number on the left side of the symbol is less than the number on the right side. (4<7)
number line - A line with numbers on it in order at regular intervals.
period - the name given to each group of three digits on a place-value chart.
place value - The value given to a digit by its position in a number.
standard form - The usual way of writing a number that shows only its digits, no words. 
word form - The form of a number that uses written words.