1.#Name? : This error occurs when a function is missing or there is some spelling mistake in formula. To correct this error check the spelling of the function. Suppose you have use SUM (A1:A5) to add a range but you forget to type the M in SUM, than this error occurs.
2.####: This error occurs when the data you have entered in a cell is too wide to fit in the cell. Suppose you have entered 198877655444 in a cell, error will show up if the column is not wide enough to fit this number. To fix this error, you just need to make the column wider by clicking on the edge of the column and dragging it towards the right.
3.#DIV/0: This error occurs when you try to divide a value by 0. For example cell A1 contains 10, cell A2 contains 0 and when you write a formula in A3= A1/A2, the error will show up.
4.#REF! : This error occurs if you have used invalid cell reference or the cell that you have used in a formula has been deleted. Suppose you have written a formula to calculate the sum is C5:= SUM (A1:A4; B1:B4) and A4 has been deleted then this error will show up. To fix this error check if the formula refers to correct or existed value.
5.#VALUE! : This error occurs if you have entered an incorrect data type or range in a cell. For example you have calculated range of cell without using the word SUM or parenthesis i.e. [=A1:A5], above error will show up.
6.#N/A: This error occurs when a value is missing or unavailable in a function. To fix this error check which value is missing or deleted in your formula.
7.#NULL! : This error occurs when you omit comma in a function. Suppose you have typed a formula to calculate sum i.e. =SUM (A1:A6 B1;B5), in this case Excel will try to find the sum that is common to both cells. The correct formula is =SUM (A!:A6, B1:B5).
8.#NUM! : This error occurs when you enter a non valid argument in a function. For example you have entered a negative number where positive number is required.