How to concatenate number and string for datetime analysis in Kusto (KQL)?

I'm trying to set some parameters in an Azure Workbook.

For some reason, I can't concatenate two values to create some dynamic date filters.

I've tried:

All of these fail with some form of:

This works, so I know that it can be done:

EDIT 1: You're right...

At first, this worked...

Then per your comment, realized I didn't need totimespan(); simplified down to...

Solution

The solution is actually simpler than you think:

print {LogBuffer}{LogBufferUnits}

print_0
00:10:00

Workbook parameters are nothing more than textual placeholders, replaced pre-execution, with the supplied values.

This is what your code looked like after the parameters were set:

print '10' + 'm'

Arithmetic expression cannot be carried-out between StringBuffer and StringBuffer

print 10 + 'm'

Arithmetic expression cannot be carried-out between I64 and StringBuffer

This following code is valid, however the result is a string

print strcat('10', 'm')

Therefore, the following code is invalid

print now() - strcat('10', 'm')

Arithmetic expression cannot be carried-out between DateTime and StringBuffer

This would have worked:

print now() - totimespan(strcat('10', 'm'))

print_0
2022-09-23T05:37:33.726665Z