Convert string into number in webi report

Hi Gurus,

I have a webi report directly on bex query where a detail Key object showing an annual salary.

Ex - GBP 123455

I want to use it as measure in the report with number value only and total in the last of column.

So, I used substr() function with length() function to obtain the number value.

But when I am trying to convert it to number using Tonumber() and dragging into report, its throwing an #error.

How we can achieve that. Please suggest.

Thanks,

Harsh