If you are thinking of becoming a Commercial Pilot then I would recommend that you do the ATPL exams. Most operators require ATPL knowledge to fly multi-crew a/c, and you are allowed to use a calculator in the ATPL nav exams, whereas you have to use the whizzi-wheel in the CPLs!
If you do the CPLs and then want to upgrade you'll end up doing the same stuff twice
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"Take-off is optional, Landing is mandatory"