How to multiply and divide decimals

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HSPT Math › How to multiply and divide decimals

Questions 1 - 10
1

77% can also be writen as ________.

Explanation

To convert a percentage into a decimal, divide the number by 100.

Instead of doing long division, simply pretend there is a decimal point at the end of the number, and then move the decimal point two places to the left.

You can think of 77 as 77.0 (or 77. - the zero doesn't matter). Now move the decimal point two places to the left.

Answer:

2

Divide:

Explanation

Examine the divisor 0.004. To make this a whole number, the decimal point needs to be moved three places right. Do this to both 0.004 and 320, adding an implied decimal point after the latter first:

Now perform this division:

3

An aircraft's cruising speed is miles per hour. How far will it travel in hours?

miles

miles

miles

miles

Explanation

The formula to calculate distance is where represents rate of speed and represents time.

In this problem, mph., and hours.

Convert the to an improper fraction:

To solve, multiply.

miles.

At its cruising speed of mph, the aircraft will travel miles in hours.

4

What is the decimal equivalent of ?

Explanation

Divide:

Answer:

5

Convert to a decimal.

Explanation

Divide the percentage by 100, or move the decimal point two places to the left:

Answer:

6

85 is what percent of 400?

Explanation

Set up the proportion statement, where is our answer, and solve:

7

Find the decimal equivalent of .

Explanation

To solve, divide:

Answer:

8

The cost of a magazine subscription has been reduced by 15%. What is the current price, if the original price was $45.00?

Explanation

First, multiply the original price by the percentage:

Then, subtract that amount from the original price:

Answer: The magazine subscription currently costs $38.25.

9

Oliver pays for a skateboard. What is the discount percentage he receives if the skateboard originally costs

Explanation

Divide .

Subtract that amount from to find the discount percentage Oliver received:

Answer: Oliver received a discount on the skateboard.

10

Evaluate:

Explanation

First, multiply, ignoring the decimal points:

Put a decimal point after the number:

Since there were five digits total (one per factor) left of the decimal points, move the decimal point in the product left five places, inserting zeroes as needed:

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