0-4 round down. 5-9 round up. The place of the rounded digit will depend on what place you are rounding to.
When the digit immediately to the right of it is 0-4 round down. If it is 5-9 round up.
Your measurement should include one estimated digit.
The last digit in a measurement indicates the level of precision or uncertainty in the measurement. It is typically an estimate and can vary depending on the instrument's precision or the person taking the measurement. The other digits are considered to be more reliable and accurate in conveying the measurement value.
Numbers that end in a digit of 4 or less should be rounded DOWN to the nearest ten.Example: 24 rounded to the nearest ten would be 20Numbers that end in a digit of 5 or more should be rounded UP to the nearest ten.Example: 28 rounded to the nearest ten would be 30
256.000
One is certain and the other in uncertain.
287 rounded to the first digit (ones) is 287.
74,312 is already rounded to the first digit (ones).
222.008 mm rounded to four significant digits is 222.0 mm
500
Dog
An uncertain digit is a digit in a measurement that is estimated or not completely reliable, often due to limitations in the measuring instrument or the precision of the measurement.