Mathematics Grade 9 15 min

Compare and order decimals

Compare and order decimals

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1

Introduction & Learning Objectives

Learning Objectives Convert decimals to their rational number form (p/q) to understand their value. Compare two or more decimals up to the thousandths place using place value. Order a set of positive and negative decimals from least to greatest and greatest to least. Use a number line to visualize and confirm the order of decimals. Apply the concept of equivalent decimals by padding with zeros to facilitate comparison. Solve word problems that require comparing and ordering decimal values derived from rational expressions. Which is a better batting average in baseball, 0.310 or 0.301? ⚾ Let's find out how to be sure! This tutorial will connect your understanding of rational numbers to the practical skill of comparing and ordering decimals. You will learn systematic me...
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Key Concepts & Vocabulary

TermDefinitionExample Rational NumberAny number that can be expressed as a fraction p/q, where p and q are integers and q is not zero. All terminating and repeating decimals are rational numbers.0.75 is a rational number because it can be written as 3/4. Decimal Place ValueThe value of a digit based on its position relative to the decimal point. The first position to the right is the tenths place, the second is the hundredths, the third is the thousandths, and so on.In the number 12.345, the '3' is in the tenths place (3/10), the '4' is in the hundredths place (4/100), and the '5' is in the thousandths place (5/1000). Equivalent DecimalsDecimals that represent the same value or the same point on a number line. You can create equivalent decimals by adding or r...
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Core Formulas

The Place Value Comparison Algorithm Given two decimals A and B, first compare their integer parts. If they are unequal, the decimal with the larger integer part is greater. If they are equal, compare the digits in the tenths place. If those are equal, compare the hundredths place, and so on, from left to right, until you find a place where the digits differ. This is the fundamental step-by-step method for comparing any two decimals. It ensures you are comparing parts of the numbers that have the same value. The Zero Padding Rule To compare decimals like 0.7 and 0.725, you can write them with the same number of decimal places by adding trailing zeros. Let A = a.d_1d_2...d_n and B = b.e_1e_2...e_m. If n < m, we can write A as a.d_1d_2...d_n0...0 where there are m-n zeros add...

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Sample Practice Questions

Easy
According to the Place Value Comparison Algorithm, which of the following comparisons is correct?
A.7.45 > 7.5
B.7.45 < 7.5
C.7.45 = 7.5
D.7.45 is unrelated to 7.5
Easy
Which of the following numbers is the smallest: 3.1, 3.01, 3.11, 3.001?
A.3.1
B.3.01
C.3.11
D.3.001
Easy
The tutorial warns about the 'Longer is Larger' fallacy. Which option correctly applies this lesson?
A.0.6 is less than 0.588 because it has fewer digits.
B.0.588 is greater than 0.6 because 588 is a bigger number than 6.
C.0.6 is greater than 0.588 because the digit in the tenths place (6) is greater than 5.
D.0.6 is equal to 0.588 because the difference is negligible.

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