if b23=10 can I use the 10 of that cell to be the numeric part of cell d? So that in this case I would be meaning d10, but if b23=12 then my d cell would be d12.
You can use =INDIRECT("D"&B23).
See LibreOffice Help on INDIRECT.
Tested with LibreOffice 6.4.7.2 (x64); OS: Windows 10.0.
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