To round 0.657, you can follow the standard rounding rule:
1. Identify the digit to the right of the desired decimal place. In this case, it is the digit in the thousandths place, which is 7.
2. If the digit in the thousandths place is 5 or greater, you round up the preceding digit. If it is less than 5, you leave the preceding digit unchanged.
In this case, the digit in the thousandths place is 7, which is greater than 5. Therefore, you round up the preceding digit, which is 6, to the next higher number. The number 0.657 rounds up to 0.66.
As for the "why" behind rounding numbers, it is a common practice used to simplify or approximate a number to a more manageable or meaningful value. Rounding can be useful in various situations, such as when dealing with measurements, calculations, or presenting data in a more concise manner.