HOW TO ROUND DECIMALS TO THE NEAREST TEN THOUSANDTH

Example 1 :

Round 5.26489 to the nearest ten thousandth.

Answer :

Underline 8, the digit at ten thousandths place.

5.26489

The digit to the right of the underlined digit is 9, which is greater than 5.

Then, add 1 to the digit 8 at ten thousandths place and drop the digit 9 to the right of 8.

Therefore, 5.26489 rounded to the nearest ten thousandths is 5.2649.

Example 2 :

Round 1.354235 to the nearest ten thousandth.

Answer :

Underline 2, the digit at ten thousandths place.

1.354235

The digit to the right of the underlined digit is 3, which is less than 5.

Then, keep the digit 2 at ten thousandths place as it is and drop all the digits to the right of 2.

Therefore, 1.354235 rounded to the nearest ten thousandth is 1.3542.

Example 3 :

Round 7.55207 to the nearest ten thousandth.

Answer :

Underline 0, the digit at ten thousandth place.

7.55207

The digit to the right of the underlined digit is 7, which is greater than 5.

Then, add 1 to the digit 0 at ten thousandths place and drop the digit 7 to the right of 0.

Therefore, 7.55207 rounded to the nearest ten thousandth is 7.5521.

Example 4 :

Round 5.42798 to the nearest ten thousandth.

Answer :

Underline 9, the digit at ten thousandths place.

5.42798

The digit to the right of the underlined digit is 8, which is greater than 5.

Then, add 1 to the digit 9 at ten thousandths place and drop the digit 8 to the right of 9.

Therefore, 5.42798 rounded to the nearest thousandth is 5.4280.

Examples 5-6 : Round each of the following numbers to the nearest ten thousandth :

Example 5 :

Answer :

In 3.42354, the digit at ten thousandths place is 5.

The digit to the right of 5 is 4, which is less than 5.

Then, keep the digit 5 at ten thousandths place as it is and drop the digit 4 to the right of 5.

Therefore, 3.42354 rounded to the nearest ten thousandth is 3.4235.

Example 6 :

Answer :

In 5.38429, the digit at ten thousandths place is 2.

The digit to the right of 2 is 9, which is greater than 5.

Then, add 1 to the digit 2 at ten thousandths place and drop the digit 9 to the right of 2.

Therefore, 5.38429 rounded to the nearest ten thousandth is 5.3843.

Example 7 :

Find the circumference of the circle whose radius is 8 cm. Use the value of π from your calculator and round your answer to the nearest ten thousandth.

Answer :

Formula for circumference of a circle :

= 2πr

Substitute r = 8.

= 2π(8)

= 16π

Using calculator for the the value of π,

= 50.26548........

Underline 4, the digit at ten thousandths place.

= 50.26548........

The digit to the right of the underlined digit is 8, which is greater than 5.

Then, add 1 to the digit 4 at ten thousandths place and drop all the digits to the right of 4.

50.26548........ rounded to the nearest ten thousandth is 50.2655.

Therefore, the circumference of the circle is about 50.2655 cm.

Example 8 :

Find the area of the circle whose radius is 12 cm. Use the value of π from your calculator and round your answer to the nearest ten thousandth.

Answer :

Formula for area of a circle :

= πr²

Substitute r = 12.

= π(12)²

= 144π

Using calculator for the the value of π,

= 452.38934........

Underline 3, the digit at ten thousandths place.

= 452.38934........

The digit to the right of the underlined digit is 4, which is less than 5.

Then, keep the digit 3 at ten thousandths place as it is and drop all the digits to the right of 3.

452.38934........ rounded to the nearest ten thousandth is 452.3893.

Therefore, the area of the circle is about 452.3893 cm².

Example 9 :

Cameron has been asked to round 1.47257 to the nearest ten thousandth. His answer is 14.7257 Explain Daniel’s mistake and what is the correct answer?

Answer :

Instead of rounding to the nearest ten thousandth, Daniel has moved the decimal place.

The correct answer is 1.4726.

Example 10 :

Olivia has rounded a number to the nearest ten thousandth. Her answer is 8.5274. Write down 10 different possible numbers that she could have rounded.

Answer :

8.52735

8.52736

8.52737

8.52738

8.52739

8.52740

8.52741

8.52742

8.52743

8.52744

Practice Questions

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