Bits and Pieces III Details- More or Less What are Benchmarks? Fractions are Decimals! When do you use decimals? You use decimals for lots of reasons but the number one reason is when you are talking about money!! What do think a decimal represents? They represent a part of something, in most cases money. When talking about money and $1.25, we save 1 is the whole dollar value and.25 is a quarter fraction of one whole dollar or 25/100. Which is less o.5 or 0.6? 0.5 is less because when you are answering a question like this you first look at the number closest to the decimal in this case 5 or 6. Since 5 is smaller than 6, 0.5 is smaller than 0.6. Which is smaller 0.47 or 0.300? The answer to this question would be When dealing with decimals you can always place 0 after the last digit and it will still be the same value (0.30 = ). So, what you could do is make 0.47, and then you have You ask the question what number is smaller 300 or 470. The answer is 300 or Which is smaller 0.6 or 0.501? 0.501 because 501 is smaller than 600. In the next problem we will look at shopping and money situations where estimation is used. Why do people estimate when they shop? People estimate when they shop so they can determine if they can afford something. Getting Ready for Problem 1.1 What is Tat Ming making for his friends? Tat Ming estimates total cost as he adds items to his cart in the grocery store. He wants to make sure he has enough money to pay the cashier. He puts the following items in his cart: Chips $2.79 Salsa $1.99 Ground Beef $3.12 Cheese $1.29 Jalapeos $0.45 Nachos!! If Tat Ming has $10.00, does he have enough money to pay for the groceries? If we round to the nearest benchmark all food items we would say the following: Chips =$2.75 Salsa = $2.00 Cheese = $1.25 Jalapenos= $0.50 Ground Beef = $3.00 If we added all of these than the amount would be $9.75. So, if he only has $10 than he can afford the groceries. What would be the exact cost of Tat Mings groceries? = 34 Put the 4 under the 2 and carry the 3 above the seven, then add =26 Put the 6 under the 1 and to the left of the 4 and carry the 2 above the 2 and the left of the 3 and then add = 9, place the 9 under the 3 and the final answer is $9.64. REMEMBER: ITS VERY IMPORTANT THAT YOU STAY LINED UP WITH THE DECIMALS!!! Problem 1.1 Estimating With Decimals For each situation decide which operation to use. Then use benchmarks and other strategies to estimate the sum or difference. A. Nick is going to Big Thrifty Acres to spend the $20 he got for a birthday present. His mom offers to pay the sales tax for him. He cannot spend more than $20. As he walks through the store, he has to estimate the total cost of all the items he wants to buy. 1. Nick chooses a game that costs $6.89. About how much money will be left if he buys the game? You would first overestimate $6.89 to $7.00 and then subtract that from $ The result is $13.00. 2. Nick finds some other things he would like to have. He finds a CD on sale for $5.99, a package of basketball cards for $2.89, a bag of peanuts for $1.59, and a baseball hat for $4.29. Does Nick have enough money to buy everything he wants? Remember to include the game at $6.89. Would you overestimate or underestimate for the situation? Text He has only $20 dollars so he would need an extra $1.25. The estimate is an overestimate. Question B Maria is saving to buy a new bicycle. The price for the bike she wants is $ She has saved $78 from babysitting. She owes her brother $5. Her grandmother gives her $25 for her birthday. She expects another $10 or $12 from babysitting this weekend. She empties her piggy bank and finds $ Should she plan to buy the bike next week? Why or why not? What is the problem asking? How much does the bike cost? How much money does Maria have and owe? The problem is asking if Maria can afford a bicycle that costs $ She has $78.00 from babysitting plus an additional $10.00 or $ She has $25.00 from her birthday. She has $13.73 from her piggy bank. She owes her brother $5.00. Marias Money Any questions? Now Go To OMCNET MATH and download Skill Sheet 1.1 from Bits III. Only due problems on first page, be sure this is done on a separate sheet of paper. They will be due on Friday.