bash: How to round/floor/ceiling non-decimals thousands number?

Question

lets say I have this number here 100675

how to turn it into 101000

all the solution I have found on google are solving decimals number.

Answer 1

The bash shell is able to do calculations internally, such as with the following transcript:

pax:~> for x in 100675 100499 100500 100999 101000; do
...:~>     ((y = (x + 500) / 1000 * 1000))
...:~>     echo "    $x becomes $y"
...:~> done
    100675 becomes 101000
    100499 becomes 100000
    100500 becomes 101000
    100999 becomes 101000
    101000 becomes 101000

This statement, ((y = (x + 500) / 1000 * 1000)), first adds 500 to make the otherwise-truncating integer division by 1,000 into a rounding division, then re-multiplies it by 1,000.