Multiplying Decimals
2.75 X 6 =
16.5
1.5 divided by 3 =
.5
.8 X 10 =
8
How do you know where to put the decimal when multiplying by a whole number?
Move it to the left in the answer the same number of times you moved it to the right in the question.
Which property of multiplication is shown here?
37.6 X 1=1 X 37.6
Commutative
Associative
Identity
Commutative Property-The order doesn't matter!
38.6 X 4 =
154.4
6.7 divided by 2 =
3.35
3.86 x 10^3 =
3860
What is the first question you ask yourself when dividing decimals?
Is the divisor a whole number?
Which property of multiplication is shown here?
6 X 12 = (6 X 2) + (6 X 10)
Commutative
Identity
Distributive
Distributive-The 6 is distributed among addition factors of 12
12.2 X 6.7 =
81.74
26.2 divided by 4 =
6.55
78.3 divided by 100 =
.783
What direction do you move the decimal when you multiply by a power of 10 and how do you know where to move it?
You move the decimal to the right as many times as there are zeros in the base 10 number you are multiplying it by.
Meg went to the ice cream shop with 2 of her friends. Her mom gave her $12.75 to spend evenly among herself and her friends. How much could each person spend?
$4.25
1.5 X 0.2 =
0.3
38.6 divided by .2 =
193
65.7 divided by 10^2 =
.657
What direction do you move the decimal when you divide by a power of 10 and how do you know where to move it?
You move the decimal to the left as many times as there are zeros in the base 10 number you are dividing it by.
Sam went snowshoeing every day for an entire week. Each day he went 4.12 miles. How many total miles did he go that week? What would be the answer rounded to the nearest tenth?
28.84
28.8
28.2 X 4.1 =
115.62
6.75 divided by 4.5 =
1.5
1.32 divided by 10^3
.00132
What should you do if there is a decimal point in the divisor?
Move the outside decimal all the way to the right in the divisor, then move it the smae number of times in the dividend. move the decimal above the division line in a straight line up. Divide like normal.
Mrs. Ward is making popcorn for her class of 28 students. She has 6.5 pounds of popcorn that she is putting in .25 pound bags. Will she have enough for her class? How many bags can she actually make?
No, she will not have enough. She can only make 26 bags.