Why does the "ls -lh" option round down a file size so much?

[bodisha]

If I look at the file /usr/sbin/mysqld with "ls -l" or include the options "-s" or "-si" on CentOS 7... it returns with the size of

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[root@centos7lab ~]# ls -l /usr/sbin/mysqld
-rwxr-xr-x. 1 root root 251284320 Dec 21  2018 /usr/sbin/mysqld
[root@centos7lab ~]# ls -ls /usr/sbin/mysqld
245396 -rwxr-xr-x. 1 root root 251284320 Dec 21  2018 /usr/sbin/mysqld
[root@centos7lab ~]# ls -lsi /usr/sbin/mysqld
610480 245396 -rwxr-xr-x. 1 root root 251284320 Dec 21  2018 /usr/sbin/mysqld
[root@centos7lab ~]# ls -lh /usr/sbin/mysqld
-rwxr-xr-x. 1 root root 240M Dec 21  2018 /usr/sbin/mysqld

But when I include the "-h" option to return it in human readable form... It rounds the size down by 10Mb... Which seems like a pretty large discrepancy!

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-rwxr-xr-x. 1 root root 240M Dec 21  2018 /usr/sbin/mysqld

Can someone explain why there's such a big difference? I understand the default block size of the "ls" command is 1000 bytes and the human readable option is 1024 bytes... But even that doesn't explain the difference

THANKS!

[tunk]

1M = 1024*1024

[TrevorH]

251284320/1024/1024 = 239.64

[bodisha]

Thanks for the replies! Just to make sure I'm clear on what you're saying

block size=1024
number of blocks =1024

block size * # of blocks = 1M

Am I understanding this correctly?

[tunk]

Not quite:
1k = 1024
1M = 1024*1024
1G = 1024*1024*1024
etc.

[TrevorH]

You asked it to show the size in megabytes. It did. But the megabytes it uses are 1024*1024 each (1048675) so your 251 million bytes becomes 240MB.

[George99]

It's getting a bit more confusing by the fact the Gnome does use 1M =1000 * 1000 so the results will be different from what ls -lh reports.