The previous one reached five, got one and went to less than five. For example, 309, 9 is greater than 5, so if you enter 1, it becomes 3 10. For example, 30 1, 1 is less than 5, so it is 300.
"Rounding" method:
Looks like one more digit than the reserved number. If the number on this number is "5" or greater, move forward one place. If the number on this digit is "4" or less, it will be discarded.
For example, 6.56, leaving one decimal place is 6.6. And 6.54, one decimal place is 6.5.
When taking decimal approximation, if the highest digit of mantissa is 4 or less, the mantissa is removed. If the highest digit of mantissa is 5 or more, the mantissa is rounded and "1" is input before it, which is called rounding method.
"Nine Chapters Arithmetic" also adopts the method of "rounding". When using the proportional method to find the vehicles that should be dispatched in each county, because the vehicles are integers, the calculation results are rounded off.