Period
A group of three digits in a number//
To make reading numerals easier, sets of
digits are set off by commas.
Billion
Million
Thousand Ones
476, 347, 506, 824
Periods
Place Value
The value of where the digit is in the
number. Each place value period has Ones,
Tens, and Hundreds.
*In 352, the place value of the 5 is “tens”// the 5 holds a
value of 5 “tens”// the 5 is in the “tens” place.
*In 7,591, the place value of the 7 is “one thousands”//
the 7 holds a value of 7 “one thousands”// the 7 is in the
“one thousands” place.
Digit
A digit is a single symbol used to make
numerals.
0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 are the ten digits we
use in everyday numbers.
*The numeral 153 is made up of 3 digits ("1", "5" and "3").
digits make up numerals
Numeral
A numeral is a symbol or name that stands
for a number.
3, 49 and twelve are all numerals.
Standard Form
A way to write numbers using the digits 0-9, with
each digit having a place value// a common way
of writing a number with commas separating
groups of three digits starting from the right.
234,586
987,654,321
234
6
Word Form
Word form of a number is a way to write
the number using words.
Standard Form: 234,586
Word Form: two hundred thirty four thousand, five
hundred eighty six
Standard Form: 987,654,321
Word Form: nine hundred eighty seven million, six
hundred fifty four thousand, three hundred twenty one
Expanded Form
A way to write numbers by showing the
value of each digit using addition.
Standard Form: 234,586
Word Form: two hundred thirty four thousand, five
hundred eighty six
Expanded Form: 200,000 + 30,000 + 4,000 + 500 + 80 + 6
(the addition form of a number)
Expanded Notation
is shown as a sum of each digit multiplied
by its matching place value.
Equivalent Decimals
Decimals that name the same number or
amount.
0.5 = 0.50 = 0.500
04.13= 4.13= 4.1300
Tenths
A decimal with one digit after the decimal
point names tenths.
.1 = one tenths
.3 = three tenths
.7 = seven tenths
Hundredths
A decimal with two digits after the decimal
point names hundredths.
.24 = twenty-four hundredths
.34 = thirty-four hundredths
.67 = sixty-seven hundredths
.03 = three hundredths
.10 = ten hundredths
Thousandths
A decimal with three digits after the
decimal point names thousandths.
.241 = two hundred forty-one thousandths
.843 = eight hundred forty-three thousandths
.951 = nine hundred fifty one thousandths
When combining the left side place values of the decimal to the right side place
values, say “and.”
54.587 = fifty-four and five hundred eighty seven thousandths
386.43 = three hundred eighty six and forty-three hundredths
Rounding
A process that determines which multiple of
10,100, 1,000, … a number is closest to.
If the digit is 5 or greater, increase the digit in the
rounding place by 1.
5.7 rounds to 6
If the digit is less than 5, leave the rounding place digit
as is and drop the digits to its right.
73 rounded to the nearest ten is 70, because 73 is closer to 70 than to 80.
Comparison Symbol:
Greater Than
Less Than
Equal To
Arrow Method
Compared to a number line, add a line to make an arrow. If the line faces right, its greater than, if
left it is less a less than sign.
Alligator Method
Draw teeth inside the symbol and whichever way the alligator’s mouth is facing is the largest
number.