Decimals Multiplying Dividing and Made Easy Bundled Unit Decimals give me a rash! Multiplying and Dividing Decimals Made Easy Bundled Unit © Created by Mike’s Math Mall

Multiplying and Dividing Decimals Multiplying and dividing decimals are two extremely important math topics. Umm… Sir, I didn’t hear anyone ask about anything! My bad! Why, you ask? Pssst! Not now, Sparky! They’re important topics because many of the numbers we encounter every day are actually decimals.

These things are Everywhere! $ We find decimals in pricing, at the gas pump, on thermometers, . and on scales. Can you think of other places we find decimals?

Part 1: Decimals Multiplying Pssst! Not now, Sparky! When’s My bad! snack time? My bad! Multiplying Decimals Part 1: Pssst! Not now, Sparky!

remember the color of undercurtains Who Remembers? If you remember how to multiply whole numbers, it will help when multiplying decimals. ? I can’t remember the color of undercurtains I’m wearing! I was afraid of that! We better do some review, Captain Undercurtains!

Multiplying Whole numbers Now it’s time for you to try some! Let’s look at the following problem: 1 1 3 2 454 × 36 1 2 7 2 4 Now it’s time for you to try some! + 1 3 6 2 1 6 , 3 4 4

Show Your Stuff! Multiply the following: 1) 782 5 × 2) 94 37 × 3,910 3,478 3) 625 85 × 53,125

So, how did you do on the multiplication practice, Sparky? Let’s Talk About it! So, how did you do on the multiplication practice, Sparky? I did great! But I’m still worried about this decimal junk! Yeah, but only to about a gazillion! I was able to ignore my sister for an entire year! Well, how good are you at ignoring things? And can you count? Then we should be good to go! Check this out!

A Little Vocabulary! Here are a couple of math terms that’ll come in handy later: Factors - Two or more numbers we multiply together. Product - The answer to a multiplication problem. Now, let’s multiply some decimals!

Multiplying Decimals × 8 3.67 . 2 9 3 6 When faced with a multiplication of decimals problem, follow these steps: Step 1: Ignore all decimals. 5 5 8 × 3.67 Step 2: Multiply normally. 1 2 . 2 9 3 6 Step 3: Count all decimal places in factors. 2 1 Step 4: In the product, place a decimal point equal to the number of places counted. *Be sure to count from right to left!

Multiplying Decimals × + 0.38 0.46 2 2 8 1 5 2 . 1 7 4 8 Remember! Let’s look at another one! 3 1) Ignore the decimals. 4 0.38 × 0.46 1 2) Multiply normally. 2 4 3 2 2 8 3) Count decimal places. + 1 5 2 There are 4 total places . 4) Place the decimal in the product. 1 7 4 8 4 3 2 1 Always “cover” a leading decimal with a zero!

That sounds a little sketchy! Let’s Talk About it! Let’s Talk About it! I think I’ll make a rap song out of that! Ignore! Multiply! Count! And place! Sparky- Spark in the house! Hey! That wasn’t so bad! Hey, everyone! My bad! That sounds a little sketchy! I never said it would be! Maybe before Sparky-Spark starts throwing down some mad rhymes, we should try some practice problems! Wow! That’s it!

Show Your Stuff! × × × × × × Multiply the following decimals. 1) 0.7 3 2) 2.8 0.8 × 3) 449 6 × 1 . 2.1 2.24 718.4 4) 1.56 × 3 4 . 5) 0. 6.8 × 9 7 6) 2.341 × 5.16 0.6708 6.596 12.07956

So, how did you do on the practice problems, Sparky? Multiplying Decimals So, how did you do on the practice problems, Sparky? I got 5 out of 6 right! That last one cracked my cranium! Because I smell some serious division coming! I guess that is possible! 5 out of 6 is pretty good, so why are you spazzing? Maybe that’s just your “undercurtains!” Division of decimals…here we come!

Dividing Decimals Part 2: SPARKY!!! Part 2: My bad! Do you smell something?

Looks like we better do some rhyming review as well, Dividing Decimals Before we divide decimals, we need to review how to divide whole numbers. The last time I checked, “divide” rhymes with “train wreck!” Looks like we better do some rhyming review as well, Sir Raps-a-Little!

Dividing Whole Numbers Let’s divide the following: 1 3 2 5 , Don’t forget the comma! 3,97 3 5 -3 9 -9 7 -6 Now it’s time for you to try some! 1 5 -15

Show Your Stuff! Divide. 54 218 1) 4 216 2) 7 1,526 1,224 3) 15 18,360

Dividing Whole Numbers Hey! Look who’s still alive after the division practice! OK, but Mr. Sparkles wants to stay in his current happy place! So, I guess our work here is done? Umm…not quite! I’ll take good care of you, Mr. Sparkles. Just follow me!

Some More Vocabulary Check out these terms! Quotient Divisor Dividend Division Box Dividend - The number you want to divide up. Divisor - The number you want to divide by. Quotient - The answer after you divide one number by another.

Dividing Decimals . . Locate the decimal in the dividend. 2 8 7 83 4 When a division problem has a decimal in the dividend, follow these steps: Step 1: Locate the decimal in the dividend. . 2 8 7 . 83 4 48 Step 2: Move the decimal straight up onto the division box. -8 3 4 -3 2 2 8 Step 3: Ignore the decimal. -2 8 Step 4: Divide normally.

Dividing Decimals . . Let’s look at another one! Remember! 8 6 3 6 3 1) Locate the decimal. 11 . 9 5 2) Move the decimal up. 8 -8 7 3) Ignore the decimal. -6 6 4 4) Divide normally. -3 3 7 Notice the repeating pattern. -6 6 Quotient = 0.863 4

happens if the divisor has a decimal! let’s light this candle! Dividing Decimals But what happens if the divisor has a decimal! Then let’s light this candle! Last example problem? That’s a great question! So let me show you a way to get out of that situation. Dividing any number by a decimal is tricky. Last one...I promise!

Dividing Decimals → . . Step 1: Locate the decimal in the divisor. 2 2 When a division problem has a decimal in the divisor, follow these steps: Step 1: Locate the decimal in the divisor. . . 2 2 9 7 5 → continued Step 2: Move that decimal to the right to create a whole number. Step 3: Move the decimal in the dividend the same number of places to the right.

Remember to move the decimal up! It’s time to show your stuff! Dividing Decimals Remember to move the decimal up! . 4 1 2 5 . 2 2 9 7 5 -8 8 2 7 -2 2 It’s time to show your stuff! 5 5 -4 4 1 -1 1

Show Your Stuff! Divide the following decimals. 7.5 0.3252 1) 7 52.5 2) 15 4.878 4.25 49.6 3) 0.8 3.4 5.96 4) 0.12

Multiplying and Dividing Decimals So, how do you feel about multiplying and dividing decimals now, Sparticus? I have this stuff covered from head to toe, sir! I can do 3 crunches in a row! Wanna see? You mean abs of steel? Oh, yeah? What’s that? Oh, darn! Gotta go! There is one thing you left uncovered! You know, your abdominal area? Oh, right! What was I thinking? © Created by Mike’s Math Mall