Program: Academy of Math
Subject Strand: Number Sense
Objective: The student will understand place value from millions to millionths.
Materials: Decimals: Place Value Chart
Time: 5 minutes
DECIMALS
One decimal place to the right of the decimal point is the "tenths" place, but one decimal place to the
left of the decimal point is the "ones" place. The "tens" place is two places to the left.
Place Value Chart
millions
hundred ten
ten
hundred
thousands hundreds tens ones tenths hundredths thousandths
millionths
thousands thousands
thousandths thousandths
The decimal point lies between the ones place and the tenths place.
(NOTE: All place value positions to the right of the decimal point have a "th" ending.)
Program: Academy of Math
Subject Strand: Addition, Subtraction
Objective: The student will add and/or subtract decimal numbers.
Materials: Decimals: Addition and Subtraction Sheet
Time: 5 minutes
DECIMALS
To add and subtract decimals, line up the decimal points, use place-holding zeros. Note: Whole
numbers are understood to have a decimal point to the right of the ones place.
12 - 4.08=
12.00
-4.08
7.92
Program: Academy of Math
Subject Strand: Multiplication
Objective: The student will multiply decimal numbers.
Materials: Decimals: Multiplication Sheet
Time: 5 minutes
DECIMALS
When multiplying decimals, don't consider decimal places until the problem is solved. Count all places
to the right of the decimal point in the problem. Count that number of places in the product (the answer)
starting from the right.
0.004 x 0.02 =
0.004
x 0.02
0.00008
Program: Academy of Math
Subject Strand: Division
Objective: The student will divide decimal numbers.
Materials: Decimals: Division Sheet
Time: 5 minutes
DECIMALS
Dividing Decimals:
If the number in a division box has a decimal, but the number outside of the division box does not
have a decimal, place the decimal point in the quotient (the answer) directly above the decimal point in
the division box.
If both the numbers inside and outside of the division box have decimals, count how many places are
needed to move the decimal point outside of the division box (the divisor) to make it a whole number.
Move the decimal point in the number inside of the division box (the dividend) the same number of
places. Place the decimal point in the quotient (the answer) directly above the new decimal point.
If the number outside of the division box has a decimal, but the number inside of the division box
does not, move the decimal place on the outside number however many places needed to make it a
whole number. Then to the right of the number in the division box (a whole number with an "understood
decimal" at the end) add as many zeros to match the number of places the decimal was moved on the
outside number. Place the decimal point in the quotient directly above the new decimal place in the
division box.
Program: Academy of Math
Subject Strand: Rounding
Objective: The student will round decimal numbers.
Materials: Decimals: Rounding Sheet
Time: 5 minutes
DECIMALS
Rounding Decimals:
PROBLEM 1: Round the following number to the nearest tenth: 0.16
Step 1: Underline the number you need to round.
0.16
Step 2: Look at the number to the right of the number to be rounded.
- If the number is “five” or more,
- Add one to the number to be rounded and change all numbers to the right to zero.
- If the number is less than “five”, leave the number to be rounded as is and change all
numbers to the right to zeros
The answer is: 0.20
PROBLEM 2: Round the following addends to the nearest thousand and then find the sum.
124,922
33,466
212,382
+ 1,445
STEP 1: Underline the number in the thousands place for each addend.
124,922
33,466
212,382
+ 1,445
Step 2: Look at the number to the right of the number to be rounded.
- If the number is “five” or more,
- Add one to the number to be rounded and change all numbers to the right to zero.
- If the number is less than “five”, leave the number to be rounded as is and change all
numbers to the right to zeros.
125,000
33,000
212,000
+ 1,000
FINALLY, Find the sum!
371,000 ANSWER
PROBLEM 3: If the number to be rounded is a 9, and the number to the right of it is 5 or higher,
change the 9 to 10. See example below:
Round to the nearest ten thousands: 196,254
STEP 1: Change the 9 to a 10 and change all numbers to the right to zeros.
1_0,000
^
10
*Place a zero in the ten thousands place and add 1 to the number in the hundred thousands place!
200,000
ANSWER