Basic Math

Compare decimals | Fifth Grade

Compare Decimals

Fifth Grade Math - Complete Guide

🔄 Equivalent Decimals

What are Equivalent Decimals?

Equivalent decimals are decimal numbers that have the same value even though they look different.

Formula:

\[0.5 = 0.50 = 0.500 = \frac{5}{10} = \frac{50}{100} = \frac{500}{1000}\]

Key Rule: Trailing Zeros

âś… Adding zeros to the RIGHT does NOT change the value

\(0.3 = 0.30 = 0.300\) (All Equal)
\(2.4 = 2.40 = 2.400\) (All Equal)

❌ Adding zeros to the LEFT changes the value

\(0.3 \neq 0.03\) (NOT Equal)
\(0.3 = \frac{3}{10}\) but \(0.03 = \frac{3}{100}\)

đź’ˇ Examples

Example 1: Are \(0.6\) and \(0.60\) equivalent?

Method 1: Convert to fractions
\(0.6 = \frac{6}{10}\) and \(0.60 = \frac{60}{100} = \frac{6}{10}\)

âś“ Yes! They are equivalent because they have the same value.

Example 2: Write three equivalent decimals for \(1.2\)

Add zeros to the right: \(1.20\), \(1.200\), \(1.2000\)

âś“ Answer: \(1.2 = 1.20 = 1.200 = 1.2000\)

⚖️ Comparing Decimals

What Does It Mean?

Comparing decimals means finding which decimal is greater (\(>\)), smaller (\(<\)), or equal (\(=\)) to another decimal.

📝 Steps to Compare Decimals

  1. Line up the decimal points vertically
  2. Add trailing zeros to make the same number of decimal places
  3. Compare whole number parts first (left of decimal point)
  4. If whole numbers are equal, compare tenths place
  5. If tenths are equal, compare hundredths place
  6. Continue until you find different digits

đź’ˇ Examples

Example 1: Compare \(5.7\) and \(5.68\)

Step 1: Line up decimal points → 5.7 and 5.68
Step 2: Add trailing zeros → 5.70 and 5.68
Step 3: Compare whole numbers → 5 = 5 (equal)
Step 4: Compare tenths → 7 = 7 (equal)
Step 5: Compare hundredths → \(0 < 8\)

âś“ Answer: \(5.68 < 5.7\) or \(5.7 > 5.68\)

Example 2: Compare \(12.45\) and \(8.99\)

Step 1: Compare whole numbers → \(12 > 8\)
Step 2: We can stop here! The whole number is greater.

âś“ Answer: \(12.45 > 8.99\)

Example 3: Compare \(0.325\) and \(0.32\)

Step 1: Add trailing zeros → 0.325 and 0.320
Step 2: Compare ones → 0 = 0 (equal)
Step 3: Compare tenths → 3 = 3 (equal)
Step 4: Compare hundredths → 2 = 2 (equal)
Step 5: Compare thousandths → \(5 > 0\)

âś“ Answer: \(0.325 > 0.32\)

📊 Using Place Value Chart

How to Use the Chart

A place value chart helps us compare decimals by aligning each digit in its proper place.

TensOnesâ—ŹTenthsHundredthsThousandths
24.567
24.582

Comparing: Tens (2=2) ✓ → Ones (4=4) ✓ → Tenths (5=5) ✓ → Hundredths (6<8) ✗
Result: \(24.567 < 24.582\)

📏 Comparing Decimals on Number Lines

Number Line Rule

📌 Basic Rule:

• Numbers to the RIGHT are GREATER
• Numbers to the LEFT are SMALLER

Example: Compare \(2.3\) and \(2.7\)

2.0────2.1────2.2────2.3────2.4────2.5────2.6────2.7────2.8────2.9────3.0

↑ 2.3 is here                                               2.7 is here ↑

Since 2.7 is to the RIGHT of 2.3 → \(2.7 > 2.3\)

📝 Steps to Compare on Number Line

  1. Identify the whole number range (between which two whole numbers)
  2. Mark the tenths between those whole numbers
  3. Locate both decimal numbers on the number line
  4. The number on the right is greater

đź“‹ Ordering Decimals

Two Ways to Order

Ascending Order (Least to Greatest):

Arrange from smallest to largest
Example: \(0.2 < 0.5 < 0.8 < 1.1\)

Descending Order (Greatest to Least):

Arrange from largest to smallest
Example: \(5.7 > 4.2 > 3.8 > 1.1\)

📝 Steps to Order Decimals

  1. Write all decimals in a place value chart
  2. Add trailing zeros to make equal decimal places
  3. Compare decimals using the comparison rules
  4. Arrange in ascending or descending order as required

đź’ˇ Examples

Example 1: Order in ascending order: \(3.8\), \(3.08\), \(3.80\), \(0.38\)

Step 1: Add trailing zeros → 3.80, 3.08, 3.80, 0.38
Step 2: Compare whole numbers first:
    â€˘ \(0 < 3\), so 0.38 is smallest
    â€˘ For the three 3's, compare tenths: 0, 8, 8
    â€˘ 3.08 has 0 in tenths (smallest among 3's)
    â€˘ 3.8 = 3.80 (equivalent decimals)

âś“ Answer: \(0.38 < 3.08 < 3.8 = 3.80\)

Example 2: Order in descending order: \(1.25\), \(1.52\), \(1.2\), \(1.5\)

Step 1: Add trailing zeros → 1.25, 1.52, 1.20, 1.50
Step 2: All whole numbers are 1 (equal)
Step 3: Compare tenths: 2, 5, 2, 5
    â€˘ 5 > 2, so decimals with 5 in tenths are larger
Step 4: For 1.52 and 1.50: compare hundredths → \(2 > 0\)
Step 5: For 1.25 and 1.20: compare hundredths → \(5 > 0\)

âś“ Answer: \(1.52 > 1.5 > 1.25 > 1.2\)

⬜ Comparing Decimals Using Grids

How Grids Work

A grid (usually 10Ă—10 = 100 squares) helps us visualize decimal values. Each square represents one hundredth (\(\frac{1}{100} = 0.01\)).

Grid Values:

• 1 column (10 squares) = \(\frac{10}{100} = 0.1\) (one tenth)
• 1 row (10 squares) = \(\frac{10}{100} = 0.1\) (one tenth)
• 1 square = \(\frac{1}{100} = 0.01\) (one hundredth)
• Whole grid (100 squares) = \(\frac{100}{100} = 1.0\) (one whole)

Comparison Rule:

The decimal with more shaded squares is greater.

đź’ˇ Example

Compare \(0.35\) and \(0.53\) using grids

Grid 1: Shade 35 squares for 0.35
Grid 2: Shade 53 squares for 0.53
Comparison: Grid 2 has more shaded squares (53 > 35)

âś“ Answer: \(0.53 > 0.35\)

đź“– Word Problems: Compare, Order, and Round

🎯 Steps to Solve Word Problems

  1. READ the problem carefully
  2. IDENTIFY the decimal numbers
  3. DETERMINE what the question asks (compare, order, or round)
  4. APPLY the correct method
  5. CHECK if your answer makes sense

Problem 1: Comparing

Sarah ran 3.45 kilometers and Tom ran 3.5 kilometers. Who ran farther?

Step 1: Identify decimals → 3.45 and 3.5
Step 2: Add trailing zeros → 3.45 and 3.50
Step 3: Compare: Ones (3=3) âś“, Tenths (4<5) âś—
Step 4: Since \(3.45 < 3.50\), Tom ran farther

âś“ Answer: Tom ran farther (3.5 km > 3.45 km)

Problem 2: Ordering

Four students measured their heights: Alex = 1.42 m, Ben = 1.4 m, Clara = 1.38 m, Diana = 1.45 m. Arrange them from shortest to tallest.

Step 1: Add trailing zeros → 1.42, 1.40, 1.38, 1.45
Step 2: All ones are equal (1=1=1=1)
Step 3: Compare tenths: 4, 4, 3, 4
    â€˘ Clara (1.38) is shortest (3 in tenths)
Step 4: For the three with 4 in tenths, compare hundredths: 2, 0, 5
    â€˘ Ben (1.40) < Alex (1.42) < Diana (1.45)

âś“ Answer: Clara (1.38 m), Ben (1.4 m), Alex (1.42 m), Diana (1.45 m)

Problem 3: Compare and Round

A book costs $12.85 and a pen costs $12.78. Which is more expensive? Round both prices to the nearest dollar.

Part 1: Compare
Compare 12.85 and 12.78:
Ones (12=12) âś“, Tenths (8=8) âś“, Hundredths (5>8) âś—
\(12.85 > 12.78\) → Book is more expensive

Part 2: Round
Round 12.85: Look at tenths (8 ≥ 5) → Round UP → $13
Round 12.78: Look at tenths (7 ≥ 5) → Round UP → $13

âś“ Answer: Book is more expensive. Both round to $13.

đź“‹ Quick Reference Guide

ConceptKey RuleExample
Equivalent DecimalsAdd zeros to the right\(0.5 = 0.50 = 0.500\)
Compare DecimalsCompare place by place (left to right)\(5.67 > 5.62\)
Number LineRight side is greater3.7 is right of 3.2
Ascending OrderSmallest to largest\(1.2 < 2.5 < 3.8\)
Descending OrderLargest to smallest\(9.1 > 6.3 > 4.2\)

âś… Remember

Always line up decimal points when comparing!

âś… Tip

Use trailing zeros to make comparison easier!

âś… Warning

More digits doesn't mean greater! \(1.1 > 1.001\)

âś… Practice

Use place value charts for clarity!

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