Multiplying Decimals
.3 x 10 =
3
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.
What property of multiplication is shown here:
7.8 X 1 + 7.8
Commutative
Associative
Identity
2.75 X 10^3
2750
What is the first question you ask yourself when dividing decimals?
Is the divisor a whole number?
What property of multiplication is shown here:
1.5 X 2 = 2 X 1.5
Commutative
Associative
Identity
Commutative
6.75/4.5
1.5
6.3 / 10^3 =
.0063
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 dividing it by.
I went to the arcade with 8 friends. My mother gave us $42.75 to share equally. How much money did we each get to spend at the arcade?
$4.75
98.6 / 100 =
.986
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 left as many times as there are zeros in the base 10 number you are multiplying by.
Jake rode his bike 42.5 miles everyday for an entire week. How many miles did he ride altogether? What would the answer be rounded to the nearest whole number?
297.5 miles
298 miles
12.42/4.6
2.7
437 / 1000
.437
What should you do if there is a decimal point in the divisor?
Move outside decimal all the way to the right in the divisor, then move it the same number of times in the dividend. Then place it above the division line where your answer will go. Finally, divided like normal.
Mrs. Ward is making hamburgers. She has 3.75 pounds of hamburger, if each hamburger she makes weighs .25 pounds, how many burgers can she make?
15 burgers