# 2.3.4 Rounding in the Real World

## Activity: How Much is It?

Suppose you want to buy a new truck. When you visit the dealership’s website, it says the cost of the vehicle you are looking at is $29,748. When you call the dealership on Thursday, the sales representative, Joe, tells you the cost is$29,750 and the next day another sales representative, Tina, informs you that the car costs $29,700. Why did the quote you were given on the cost of the truck change? ### Discussion Round the website cost to the closest$10. Then round the website cost to the closest $100. ### Answer Here’s how the variation in the quotes happened: Rounding to the closest$10 (this is the same as rounding to the tens): The digit 4 is in the tens place. Looking to the next smaller place value (to the right), the digit is an 8. Since 8 is larger than 5, we round up the 4 to 5 in the tens place. Finally, we replace the units digit with 0 (because this place is to the left of the decimal point). The rounded number is $29,750. This explains Joe’s quote. Rounding to the closest$100 (this is the same as rounding to the hundreds): The digit 7 is in the hundreds place. Looking to the tens place (to the right of the 7), the digit is a 4. Since 4 is less than 5, we leave the digit 7 unchanged and replace the digits after the 7 with zeros. The rounded number is \$29,700. This explains Tina’s quote (which is more appealing than Joe’s since it’s less).

Want to be a mathionaire? Check out this rounding game [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] for a little extra practice!