So what’s the point? Get it? © Mike’s Math Mall PowerPoint

We round numbers to make them easier to use and understand while keeping them close to their actual value. Hey! That sounds a lot like estimating. Sure! Your last math test grade was actually a %. Can you give me an example? That’s right! We round to help us estimate. But I got a 54% on that baby! Right! Your teacher rounded the grade to make it easier to use and understand. Umm… About that test… Bad day? Bad unit… Fractions! Ouch!

Sales tax – always rounded Sales tax – always rounded to the nearest penny. Mental math – rounding numbers helps us do math in our heads. Time/Distance/Amount – rounded for easier understanding. Here are some real-world examples where numbers are rounded:

o n e s t e n s h u n d r e d s thousands ten thousands hundred thousands m i l l i o n s t e n t h s h u n d r e d t h s t h o u s a n d t h s 5, 267, (Sample number) Can you name all of the place value positions below?

Sparky! You can do this! That’s a lot of places for one kid to remember! Confidence is the key! Head… about…to explode!

Part 2:

You guessed correctly, so hopefully you have all your place values down! I’m guessing in order to round numbers, you really need to understand place value. I think I do, and my brain pain is going away! That’s my champ!

Let’s round some whole numbers! Example 1: Round the following number to the nearest hundred. Step 1: Underline the hundred’s place. Step 2: Look at the number to the right of the underlined digit. the underlined digit. 5,368

Step 3: If the number on the right is 5 or more, add one to the underlined number, and then turn the rest to the underlined number, and then turn the rest of the digits on the right into zeros. of the digits on the right into zeros. 5,368 Example 1 continued: Round the following number to the nearest hundred. Step 3: If the number on the right is 4 or less, leave the underlined number alone, and turn all digits on underlined number alone, and turn all digits on the right side of the underlined number into zeros. the right side of the underlined number into zeros. = 5,400 or

Example 2: Round the following number to the nearest ten thousand. 683,261 Step 1: Underline the ten thousand’s place. Step 2: Look at the number to the right of the 8. Step 3: Leave 8 alone because 3 is “four or less.” Step 4: All numbers to right of the underlined number turn into zeros. number turn into zeros. 0,000 = 68

496 Step 1: Underline. Step 2: Look to the right of 9. Step 3: Round the 9 up to 10 and carry the 1 over to the 4, making it a 5. to the 4, making it a 5. Step 4: All numbers to right of the underlined number turn to zero. number turn to zero. = 50 0 Let’s practice! Example 3: Round the following number to the nearest ten.

Round the following numbers to the place indicated. 1) thousands; 14,023 3) millions; 63,502,019 5) hundred thousands; 181,215 7) tens; $ ) tens; 21,485 4) hundreds; 757,839 6) ten thousands; 397,216 8) hundreds; 7,985 14, ,80064,000,000 21, , ,000 $ ,000

Part 3:

We follow the exact same steps, but at the end, instead of turning numbers into zeros, we just remove them! I think I get rounding, but we still need to round decimals. Is there any difference? Sounds reasonably painless! Check this out!

Example 1: Round the following decimal to the nearest hundredth Step 1: Underline. Step 2: Look to the right of 5. Step 3: The 5 stays the same. = 1.25 Step 4: Cut off all numbers to the right of the underlined number. underlined number. 2

Example 2: Round the following decimal to the nearest tenth Round the 4 to a 5, and remove all digits to the right of the underline number. =

Example 3: Round the following money amount to the nearest penny. $3.985 Round the 8 up to a 9. Remove the 5. Don’t forget the dollar sign! = $3.99 Let’s practice!

Round the following decimals to each underlined place $ $ or 1.0 $7.50$860.00

Round the following numbers to the indicated place. 1) thousandths; ) hundredths; ) thousandths; ) nearest penny; $ ) tenths; ) tenths; ) hundredths; ) nearest dime; $ $ or 5.00 $65.50

My job here is done! So, how’d you do on the practice problems, Sparky? I did great, sir, and I’m going to try rounding everything “up” the next time I eat! Well, the next time you go shopping, how about rounding “up” to the next shirt size? But then no one will be able to see my well-rounded belly! © Mike’s Math Mall