1. ALGEBRA READINESS LESSON 1-4 Warm Up Lesson 1-2 Warm Up

2. ALGEBRA READINESS LESSON 1-4 Warm Up Lesson 1-2 Warm Up

3. ALGEBRA READINESS To round numbers: 1.Identify the place you are rounding to, and place a box around it. 2.Check the digit to the right. If the digit to the right is greater than or equal to 5, the number in the box increases by one. If the digit to the right is less than 5, then the number in the box stays the same. 3.Keep everything before the box. Everything after the box becomes zero. If the zeroes come at the end of a decimal, they can be dropped. Example: Round 4,535 to the nearest hundreds place. Example: Estimate 13.56 to the nearest tenths place. Estimating for Reasonableness (1-4) How do you round numbers? 4, 5 2 5 __, __ __ __ 4 5 00 The number to the right is less than 5, so 5 stays the same. 1 3.5 6 __ __. __ __ 1360 The number to the right is greater than 5, so add one to 5 (5 + 1 = 6). Every number after the box becomes zeroes all the way to the decimal Drop zeroes that come at the end of a decimal (simplify).

4. ALGEBRA READINESS Estimate 97 – 21 by rounding to the nearest ten. So 97 – 21 80. 97 7 ≥ 5, so round up. 100 – 21 1 < 5, so round down. – 20 80 Estimating for Reasonableness LESSON 1-4 Additional Examples

5. ALGEBRA READINESS Compatible Numbers: numbers that are easy to compute mentally. To estimate using compatible numbers, change your numbers to compatible numbers that you can work with in your head that are close to the original numbers. For example, instead of multiplying 5.21 by 78.03, it’s easier to think about multiplying 5 times 80. When we estimate, we can say that the product of 5.21 and 78.03 is about 5 times 80 or 400. Most of the time, you will be asked to round to the nearest whole number. To round to the nearest whole, round to the ones place, and drop the decimal part of your number. Example: Estimate the sum of 10.93 and 3.25.  Estimating for Reasonableness (1-4) What are compatible numbers ? How do you use compatible numbers to estimate? How do you estimate to the nearest whole? 10.93 + 3.25 14.18 11 + 3 14

6. ALGEBRA READINESS Estimate 358 ÷ 9 by using compatible numbers. So 358 ÷ 9 40. 358 ÷ 9 360 ÷ 9 = 40 9 is compatible with 36. 360 ÷ 9 Change 358 to 360 because 360 is easier to use mentally. Estimating for Reasonableness LESSON 1-4 Additional Examples

7. ALGEBRA READINESS Jana buys a sandwich for $4.64, a drink for $3.12, and a snack for $2.29. The cashier says that the total is $12.85, including $.80 tax. Is this reasonable? Explain. No. The total should be close to $11, so $12.85 is not reasonable. Estimate by using compatible numbers. 4.64 + 3.12 + 2.29 + 0.80 4.5 + 3 + 2.5 + 1 = 11 Estimating for Reasonableness LESSON 1-4 Additional Examples

8. ALGEBRA READINESS Estimate. Round each number the nearest whole first. 1. 263 – 107 + 6212. 37 + 21 Estimate using compatible numbers. 3. 898  51 4. 211  29 5. Rob received 39 e-mails yesterday. If he received the same number every day, about how many e-mails will he receive in March? 1,000 60 45,0006,000 1,200 Estimating for Reasonableness LESSON 1-4 Lesson Quiz