Rounding off a decimal number to a given number of decimal places is the quickest way to approximate a number. For example, if you wanted to round off $2,6525272$ to three decimal places, you would:
- count three places after the decimal and place a $|$ between the third and fourth numbers
- round up the third digit if the fourth digit is greater than or equal to $5$
- leave the third digit unchanged if the fourth digit is less than $5$
- if the third digit is $9$ and needs to be round up, then the $9$ becomes a $0$ and the second digit rounded up
So, since the first digit after the $|$ is a $5$, we must round up the digit in the third decimal place to a $3$ and the final answer of $2,6525272$ rounded to three decimal places is $2,653$.