Bash round whole numbers up, down or to nearest hundreds - bash

Question

There is a range of whole positive numbers like
827818
6574762
685038
55326902
What I need, for example, to round down to hundreds to get accordingly
827800
6574700
685000
55326900
Many ideas how to round up, down or nearest hundreds using Javascript, for example
Math.floor(number / 100) * 100;
but is it possible to do the same in Bash ?

Answer 1

It's not entirely clear what is meant by "in Bash", but perhaps one of :
$ cat input
827818
6574762
685038
55326902
$ awk '{printf "%d00\n", $0 / 100}' input
827800
6574700
685000
55326900
or (if all the values are greater than 100!):
while read x; do echo "${x%[0-9][0-9]}00"; done < input
If you want to handle the case where values are less than 100 and deal with negative values, you could do:
while read x; do if test "${x#-}" -gt 100; then echo "${x%[0-9][0-9]}00"; else echo 0; fi; done < input
but it's almost certainly better to stick with awk.

Answer 2

To round to the nearest 100, use (number + 50) / 100 * 100.
You can modify each line to this calculation, then run those expressions through bc to evaluate them.
sed 's|.*|(&+50)/100*100|' file | bc

Answer 3

For rounding down you can also rev the full number and use cut -c 1-2 on the output, which you can then rev again to obtain the full number's last two digits. Then you can do calc or bc (full number - first output) to round down to nearest 100.
Or you can remove the last two digits of the full number with bc using scale=0 (or no scale) and divide by 100, after which you can just multiply by 100 again;
DIV_100=$( echo "123456789/100" | bc ) && echo "$DIV_100*100" | bc
and in loop
while read -r line; do
echo "$line" > full_number_1.txt
FULL_NUMBER=$(<full_number_1.txt)
DIV_100=$( echo "$FULL_NUMBER / 100" | bc )
echo "$DIV_100 * 100" | bc >> output_file
done < input.txt
Or use echo ${...%??}
echo "${number%??}*100" | bc
..loop..
while read -r line; do
echo "${line%??}*100" | bc >> output
done < input.txt
Many options here for rounding down.
Rounding up will require some alterations but is equally possible in many ways. For example:
DIV_100=$( echo "123456789/100" | bc ) && echo "($DIV_100*100)+100" | bc
and in loop
while read -r line; do
echo "$line" > full_number_1.txt
FULL_NUMBER=$(<full_number_1.txt)
DIV_100=$( echo "$FULL_NUMBER / 100" | bc )
echo "($DIV_100 * 100)+100" | bc >> output_file
done < input.txt
or with echo ${...%??}
echo "(${number%??}*100)+100" | bc
..loop..
while read -r line; do
echo "(${line%??}*100)+100" | bc >> output
done < input.txt