Inumber not working in calculated column.

Hi,

I have a particular column [Search Impr. share] that has three possible values:

<10%

--

x%

If the column has x%, I want to be able to find out the eligible impressions. This would be created by dividing [actual impressions] column by [Search impr. share.]. I would create a calcuated field for this once I know which rows to use.

I tried creating a calculated column using ISNumber but I get all results as "No"

Eligible Impession = if(isnumber('Weekly Search'[Search Impr. share]),"Yes","No")

If I try to extract the first character of the [Search Impr. share] and multiply it by 1 (to convert it to a number), PBI doesn't accept it as the column can have both string and numeric values.

can anyone help with this, please.

Thanks.