Clarification: For b, with "a string" it seems you accept both string arrays and char arrays. For c, with "matrix" it seems you require a numeric array — this is different from MATLAB's definition of a "matrix".
Thank you David Verrelli. I have modified the problem description to try to reflect that.
Summing Digits within Text
Back to basics 11 - Max Integer
Rotate a Matrix by 90 degrees
Is this triangle right-angled?
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