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## Decimal Multiplication

#### Grade 5 Base Ten - 5.NBT.7

Tips for Decimal Multiplication - The concept of a decimal value itself is a complicated concept; however, the multiplication of decimals can get more complicated if taken lightly. Decimals are just another way to communicate a value that is not a full whole number value. It is similar to percentage and fractional values, just a different way to express that value. There are a number of things that you should keep in mind when multiplying decimal values. If you treat the values like they were whole numbers throughout the process and just come back to the decimal portion later, it will make it easier for you. Our first piece of advice is just to ignore that decimal point all together. Just look at your decimal value and count how many digits are found to the right of the point. Keep a mental note of the value. Sometimes, I recommend that students write the value down and circle it before they go any further. Then, like we initially said, just multiply everything as if it were all your run of the mill whole number multiplication. Once you have determined the whole number product, place the decimal point in the result before the total sum of decimal places. These worksheets will help you learn how to find the products of decimal values.

### Printable Worksheets And Lessons  #### Homework Sheets

The placement of that decimal point is the single most important concept here for kids.

• Homework 1 - We will place the decimal point in the answer by starting at the right and moving a number of places equal to the sum of the places in both numbers multiplied.
• Homework 2 - See what happens when you jam a whole number in there.
• Homework 3 - We focus on tenths multiplied by hundredths.

#### Practice Worksheets

I threw the alignments off ever so slightly to make sure that students truly get the skill down.

• Practice 1 - Find the final value of the following decimal product problem.
• Practice 2 - These expand to the thousandths place.
• Practice 3 - Which of these will take you over the top?

#### Math Skill Quizzes

The entire setup is horizontal to make sure kids get the handle on the skill here.

• Quiz 1 - Example: 68.5 × 6.21
• Quiz 2 - These numbers are larger than you would expect.
• Quiz 3 - Follow these all the way through.

### Why This Skill Matters?

There are many times you will use this skill in your everyday life and when you need to know it, it is critical that you know what you are doing. If you design anything that requires measurements, you may use this skill. Many of the new sonic and laser based measurement tools make taking length measures simple, but they also leave all the measures in a decimal value, because most manufacturers can claim the product is more accurate than if it were in fractional form. Which yes, allows them to claim their product is more precise, but it leaves the customer with the need to multiply decimals and whole numbers all the time. You will also be looking for decimal products almost all the time when you are working with money and finances. Since money is usually stated in dollar and cents values, they lend themselves to the decimal format. This concept is evident every time you are trying to calculate your paycheck for the weekly in an hourly payment situation. You multiply your pay rate by the number of hours that you have worked. Once you get a job, you will see how this concept will directly apply to you. It will be the first time that you learn how taxes really eat into your paycheck as well.