Using a Rule to Find Decimal Products (Quiz)

Charlie is evaluating the product of 0.09 and 0.05. He multiplies, and before placing the decimal, arrives at an answer of 45. After considering the decimal placement, what is Charlie's final answer?

0.0045

What is the product of 0.42 and 0.03?

0.0126

The product of which expression contains four decimal places?

14.2 X 0.784

The product of 84.12 and which number will have three decimal places?

19.3

Quincy feeds his dog 2.75 cups of dog food each day. Each cup of dog food costs $1.25. He multiplies the numbers together to determine how much it costs to feed his dog each day. Which expression will result in the best estimate for Quincy to use to check his multiplication?

3 X 1

Brenna is buying 4.25 feet of ribbon for $1.95 a foot. She determines the product of the two numbers to determine the actual cost of the length of ribbon. Which expression will result in the best estimate for Brenna to use to check her multiplication?

4 X 2

Jeremiah flies an airplane for 2.7 hours at an average speed of 304.6 miles per hour. How far did Jeremiah fly?

822.42 miles

Anna drove at a constant rate of 63 miles per hour for 3.2 hours. She determined she drove 201.6 miles. Which best explains the reasonableness of Anna's answer?

Anna's answer is reasonable because 60 X 30 is 180, and 180 is reasonably close to 201.6.

Callie evaluated the expression 0.42 X 4.73 using the steps shown below.

Callie incorrectly placed the decimal.

The length of a rectangular wall is 16.5 feet. The height of the wall is 8.625 feet. Cameron determines the area of the wall to be 1423.125 square feet. Which best explains the reasonableness of Cameron's solution?

Cameron's solution is unreasonable because 17 X 9 is 153, and 153 is not close to his product.

One floor of a dollhouse is 1.6 feet tall. The dollhouse contains two levels of living areas and an attic for a total of 2.5 floors. Jaime estimates the height of the dollhouse by computing 2 X 3. How does her estimate compare to the actual height of the dollhouse?

Her estimate is greater than the actual height because both factors were rounded up.

Jason walked for 0.75 hours at a rate of 3.4 miles per hour. He determines that he walked 0.255 miles. Which best explains Jason's mistake?

Jason likely misplaced the decimal, because , and if the decimal was between the 2 and the 5, the number would be near 3.

Jonathan pays $1.90 per pound for potatoes. He buys 8.3 pounds of potatoes. He determines that he will pay $15.77, before tax, for the potatoes. Which best describes the reasonableness of Jonathan's solution?

Jonathan's answer is reasonable because is 2 X 8 = 16, and 16 is close to 15.77.

Mikayla evaluated the expression 0.86 X 23.4 using the steps shown below.

Mikayla moved the decimal incorrectly.

A drink was spilled on the math problem shown below.Ron remembers that the second factor was a decimal. Based on the placement of the decimals in the first factor and the product, which must be true of the second factor?

The decimal could be two-tenths.

Karissa determines the area of her desk by multiplying 45.72 centimeters and 60.95 centimeters. She states that the area is 2786.634 square centimeters. Which best describes the reasonableness of Karissa's solution?

The solution is reasonable because 50 X 60 is 3,000, which is close to the computed area.

Wyatt hiked for 4.7 hours at a rate of 2.9 miles per hour. He determined that he hiked 13.63 miles. Which best explains the reasonableness of Wyatt's answer?

Wyatt's answer is reasonable because is 15, and 15 is close to 13.63.

How many decimal places are in the product of the expression below? 25.6 X 14.2

two