When to use it
Use it when rounding a number to a given place value to decide whether to round up or keep the digit the same.
Example
Rounding 4.37 to the tenths place, look at the hundredths digit 7. Seven is five or more, so raise the 3 to 4, giving 4.4.
Common mistake
Rounding up when the digit is exactly 4. Four or less means leave the digit as it is.