1. Estimating Decimals Textbook page 96

2. What is clustering? Clustering means rounding the numbers to the same value. The numbers 18, 21, and 19 are all close to 20. To find the sum we could estimate: 18 20 2120 +1920 60

3. Example 1: Estimate the sum of the numbers 198.45 210.6 194.4 [Clustering means rounding the numbers to the same value.] To find the sum we could estimate: 198.45200 210.6200 +194.4200 600

4. Example 2: Estimate by rounding to the indicated place value. (A)3.92 + 6.48; ones 4 + 6 10 (B) 8.6355 – 5.039; hundredths 8.64 - 5.04 line up the decimals 8.64 -5.04 3.60

5. Example 3: Estimate by using compatible numbers. (A)26.76 x 2.93 25 x 3 75 (B) 42.64 ÷ 16.51 45 ÷ 15 3

6. What is front-end estimation? Example 4: Estimate using front- end estimation. Front-end estimation means to use only the whole number part of the decimal. 9.99 + 22.89 + 8.3 9.999 22.89 22 +8.38 39