What is 3,978 rounded to the nearest hundred?

1. Locate the hundreds place in 3,978, which holds the digit 9. 2. Look at the digit to its right, which is 7. 3. Since 7 is greater than or equal to 5, add 1 to the hundreds digit: 9 + 1 = 10. 4. Since the hundreds digit cannot hold 10, that 10 carries into the thousands place, turning 3 thousands into 4 thousands and resetting the hundreds digit to 0. 5. Replacing the remaining digits with zeros gives 4,000. 6. 3,900 comes from rounding down instead of up, and 3,980 comes from rounding to the nearest ten instead of the nearest hundred. _Source: OpenStax Prealgebra (CC BY 4.0), Ch 1 "Whole Numbers", section 1.1 Introduction to Whole Numbers_