Return the left, and right sides of a variable separately

Summary

i need to return the numbers of the cost center, and then the description in the next column

Content

Example

 

for the left side in OBI 

=Left([Open Reqs].[Req. Organization Level 5];4)

in order to just return the first 4 numbers

 

for returning the right before the first 5 spaces i had to create a variable 

=Length([Open Reqs].[Req. Organization Level 5])

then apply the variable to return the cost center name 

=Right([Open Reqs].[Req. Organization Level 5];[_m_len]-5)

Not sure how to do this in BO....any ideas? Thank you!!