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# Rounding, Estimation, and Decimal Equivalents for CBEST Exam Study Guide (page 2)

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Find the answer by walking through the Success Steps.

1. The digit is 9, so it will either stay 9 or go to 0.
2. The digit 8 is to the right of 9.
3. This step does not apply; 8 is not less than 5.
4. The 9 goes up one because 8 is more than 5.
5. Change 9 to 0 and change 2 to 3. The answer is d, 4,313.0.

(Steps 6 and 7 don't apply.)

#### Practice

Now try a few more rounding questions.

1. Round 45.789 to the nearest hundredth.
2. Round 296.45 to the nearest ten.
3. Round 345,687 to two significant digits.

1. The digit you need to look at is 8; it will either stay 8 or go up to 9. The number 9 is to the right of 8; 9 is more than 5, so you change 8 to 9. The answer is 45.79.
2. The digit is 9; the 9 will either stay 9 or go to 0. The number 6 is to the right of 9; it is more than 5, so change 9 to 0 and apply step 5, raising the 2 to the left of 9 to 3. Now apply step 7, and change digits to the right of the tens place to 0. The answer is 300.
3. Here you need to apply step 6. Two places from the left is the ten thousands digit, a 4. Now apply step 1 and work through the steps: The digit is 4, so it will either stay 4 or go up to 5. Since the right-hand neighbor is 5, change the 4 to 5. Now apply step 7 and change all digits to the right of your new 5 to zero. The answer is 350,000.

### Estimation

Estimation requires rounding numbers before adding, subtracting, multiplying, or dividing. If you are given numerical answers, you might just want to multiply the two numbers without estimation and pick the answer that is the closest. Most likely, however, the problem will be more complicated than that.

#### Sample Estimation Question

1. 42 × 57 is closest to
1. 45 × 60
2. 40 × 55
3. 40 × 50
4. 40 × 60
5. 45 × 50

Here's how you could use the Success Steps to answer the sample question:

1. You can round 42 down and 57 up, resulting in choice d.
2. Rounding the numbers to one significant digit yields d also.
3. Eliminate choices. a. Eliminated: 45 is further from 42 than 40 is. b. Maybe. c. Eliminated: 50 is further from 57 than 60 is. e. Eliminated: 45 is further from 42 and 50 is further from 57.
4. Check the remaining answers. The product of choice b is 2,200. The product of choice d is 2,400. The actual product is 2,394, which makes choice d the closest, and therefore the correct answer.

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