3.1 – 3.4 Pre-Test Please grab your clicker and a scrap piece of paper!!

CHAPTER 3: DECIMALS AND EQUATIONS Section 3.1: Rounding & Estimating

Rounding!!!!

Practice!! Round to the nearest tenth Is the number after the tenths place 5 or larger? Yes, so we round up! 4.3!!! Round to the nearest Integer Is the number after the Integers place 5 or larger? No, so we do not round up! 4!!!

You Try!! Round to the nearest hundredth Is the number after the hundredths place 5 or larger? Yes, so we round up! 4.27!!! Round to the nearest thousandth Is the number after the Integers place 5 or larger? No, so we do not round up! 4.268!!!

Estimating!!! You can estimate an answer before you calculate it to make sure your answer is reasonable. If the answer is close to the estimate, then you know it is probably correct? The symbol “≈” means “is approximately equal to”. Example: Estimate 127 ≈ 130

Practice!! Calculation Estimate $135.95≈$140 $ 15.90≈$ 20 +$24.05≈$ 20 $275.90$180 The answer is not close to the estimate. The answer is not reasonable. Calculation Estimate ≈ ≈ The answer is close to the estimate. The answer is reasonable. Estimate to find if the answer is reasonable.

Estimate – You Try!! ≈ – – 230 ≈ ≈ – – 180 ≈ 250

Front-End Estimating Front-end estimation is often closer to the exact sum than estimation by rounding. First add the front-end digits. Round to estimate the sum of the remaining digits Total ≈ 5.50

Front-End Estimating – You Try!! Total ≈ Total ≈ 11.00

Clustering You can also use clustering to estimate the sum of several numbers that are close to one value. Estimate the following using clustering: All the values are around 15. So we do 15 times 4! 15(4) ≈ 60!!!!

Clustering – You Try!!! All the values are close to (3) ≈ All the values are around (5) ≈ 125

Homework!!! Page 125: 1-6, 9-12, 15-24, 27-30, 35-37