Round and Compare Decimals
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What you will learn
- 1Compare decimals to the tenths and hundredths using < > =
- 2Round decimals to the nearest whole number
- 3Round decimals to the nearest tenth
- 4Order a set of decimals from least to greatest
Mini Lesson
Decimal numbers can be compared and rounded just like whole numbers. When comparing, align the decimal points and work digit by digit from left to right. When rounding, identify the target place and look at the digit immediately to its right.
Comparing Decimals
- Align decimal points, then compare the digits in each place value from left to right.
- 0.6 > 0.59 — the tenths digit 6 is greater than 5, so 0.6 wins even though 0.59 has more digits.
- Use <, >, or = to record the relationship: 0.4 = 0.40, because 4 tenths = 40 hundredths.
Round to the Nearest Whole Number
- Look at the tenths digit (the digit right after the decimal point).
- If the tenths digit is 5 or more, round up: 2.7 → 3.
- If the tenths digit is less than 5, round down: 3.2 → 3.
Round to the Nearest Tenth
- Look at the hundredths digit (the second digit after the decimal point).
- If the hundredths digit is 5 or more, round the tenths up: 0.47 → 0.5.
- If the hundredths digit is less than 5, keep the tenths digit: 0.43 → 0.4.
Words to know
Decimal
A number that uses a decimal point to show parts of a whole
e.g. 0.47 is a decimal.
Round
To replace a decimal with the nearest whole or tenth
e.g. Round 0.47 to the nearest tenth: 0.5.
Compare
To decide which decimal is greater, less, or equal
e.g. Compare 0.47 and 0.5 by lining up place values.
Place value
The value a digit has based on its position
e.g. Place value tells me 0.5 > 0.47.
Number line
A straight line that shows numbers in order
e.g. I plot 0.47 on the number line to compare.
Tip: a number line helps you see which whole number or tenth a decimal is closest to. Plot the decimal and check which end it is nearer to.
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