Chapter 1 - XYZ Custom Plus

Rounding and Estimating1.3Introduction . . .Many times when we talk about numbers, it is helpful to usenumbers that have been rounded off, rather than exact numbers.For example, the city where I live has a population of 43,704. Butwhen I tell people how large the city is, I usually say, “The populationis about 44,000.” The number 44,000 is the original numberrounded to the nearest thousand. The number 43,704 iscloser to 44,000 than it is to 43,000, so it is rounded to 44,000.We can visualize this situation on the number line.Welcome toSan Luis ObispoFounded 1772Population 43,704ObjectivesA Round whole numbers.B Estimate the answer to a problem.FurtherCloser43,000 43,704 44,000A RoundingThe steps used in rounding numbers are given below.Strategy Rounding Whole NumbersTo summarize, we list the following steps:Step 1: Locate the digit just to the right of the place you are to round to.NoteAfter you have usedthe steps listed hereto work a few problems,you will find that the procedurebecomes almost automatic.Step 2: If that digit is less than 5, replace it and all digits to its right withzeros.Step 3: If that digit is 5 or more, replace it and all digits to its right with zeros,and add 1 to the digit to its left.You can see from these rules that in order to round a number you must be toldwhat column (or place value) to round to.Example 1Round 5,382 to the nearest hundred.Solution There is a 3 in the hundreds column. We look at the digit just to itsright, which is 8. Because 8 is greater than 5, we add 1 to the 3, and we replacethe 8 and 2 with zeros:Practice Problems1. Round 5,742 to the nearesta. hundredb. thousand5,382 is 5,400 to the nearest hundred8n8n8888nGreater than 5 Add 1 to Put zerosget 4 hereExample 2Round 94 to the nearest ten.Solution There is a 9 in the tens column. To its right is 4. Because 4 is lessthan 5, we simply replace it with 0:94 is 90 to the nearest ten8n8nLess than 5Replaced with zero1.3 Rounding and Estimating2. Round 87 to the nearesta. tenb. hundredAnswers1. a. 5,700 b. 6,0002. a. 90 b. 10025