Review Questions Please record the answers on your paper. Compare the following decimals: Compare using table model: 0.09 ___ 0.9 Compare using number line 6.92 ___ 6.4 2. Round each decimal to the nearest whole number . 9.36 9.92 3. Write this in words: 2.12081 < < = 9 = 10 Two and twelve thousand eighty-one hundred thousandths

1-3 Comparing & Ordering Decimals Math Course 1 Mrs. Ymas

Target Goal: Word Power: Compare decimals using models Use place value Number Line

Using Models to Compare Decimals Draw models for 0.4 and 0.36. Which is greater? A greater area is shaded for 0.4 so 0.4 > 0.36.

Using Decimal Models Draw models for 0.7 and 0.27.

Draw models for the following: 0.09 and 0.9 0.5 and 0.43

Decimals on the Number Line Number Line – an infinite line that shows the place/order of numbers.

1) 0.4 and 0.5 0.5

3) 0.2 and 0.02 0.2

5) 2.1; 2.53; 2.3; 2.5 2.1; 2.3; 2.5; 2.53

7) 0.49; 0.34; 0.4; 0.3; 0.38 0.3; 0.34; 0.38; 0.49; 0.4

9) 1.42___ 1.4 1.42 > 1.4

11) 0.3___0.27 0.3 > 0.27

13) 0.048___0.408 0.048 > 0.408

15) 17.1; 17.7; 13.7 13.7; 17.1; 17.7

17) 9.2; 9.02; 9.209; 9.024 9.02; 9.024; 9.2; 9.209

Order the decimals: 2.1; 2.34; 2.41; 2.3; 2.12 41.90; 41.89; 41.09; 41.78; 41.88

Brain Break Try writing on air: 8 in your hands and 0 in your feet.

1-4 Estimating with Decimals Word Power: Compatible numbers Front-end estimation Approximation (Approximately) Estimate

Round UP or DOWN??? When do we round down? When do we round up?

Estimate by ROUNDING (whole numbers)… Use the symbol ≈ “approximately” 10.93 15.4 x 3.35 2.6

Estimating with Compatible Numbers Compatible numbers – numbers that are easy to compute mentally. (useful in getting products & quotients) To make it easier to multiply 5.21 x 78.03 = 5 x 80 To make it easier to divide 29.56 x 4.13 = 28÷ 4

Using Front-End Estimation Step 1: Add the front digits Step 2: Look at the decimals and adjust the estimate STEP 1 5.98 0.81 + 9.02 3.45 4.39 STEP 2 5.98 0.81 + 9.02 3.45 4.39 About 1 21 21 + about 3 ≈24

Exact or Estimate??? Record of attendance at a football game. Amount of money you plan on spending when shopping. Amount of money a store cashier earns each hour. The time it takes to get to school Describe two situations, one that needs only an estimate and one that needs an exact answer. Explain why.

Be ready for a Quiz (1-1 to 1-5) on Thursday. Homework: Practice 1-3 and 1-4 Be ready for a Quiz (1-1 to 1-5) on Thursday.