Use of Multi Function In one Cell

Q&A_1 Need Sum of all digit from a cell        Use of left, right & mid function together

Q&A_2 Extract First Name with 3 Method       Use of Left, Find, Replace,Mid

Q&A_3 Extract Last Name with 3 Method when 2 words in a Name     Right, find, len,replace,left, SUBSTITUTE used here

Q&A_4 Extract Last Name        Use of Right, Trim, Len, Find, Substitute