The F4 key does that, if you press it while typing in the cell reference.
Yes, you can use as many combinations of absolute and relative references as you like on the same worksheet.
A relative cell reference is one that will change to a different cell if you copy the formula. An absolute reference is one that will always use the same cell. For example, say you have a percentage in cell B1 that you want to add to all the cells from A3 down. In cell B3 you could use the formula '=A3*(1+$B$1)'. If you copy this formula to the cells below B3, the reference to A3 will change to be the cell immediately to the left, because it is a relative cell reference. By adding the $ symbol before the B and the 1, however, an absolute reference is created. It will always refer to cell B1.
Excel uses relative (A2), absolute ($A$2), and mixed ($A2) cell references.
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Yes. Formulas can contain all sorts of things, including absolute and relative cell references.
No, they are called absolute references.
A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.A formula can be copied no matter what type of references are in it. It depends on what the formula is doing. Most copied formulas will have relative references in them or at least have mixed references. A formula that consists solely of absolute references will not change if copied, but a formula with some absolute references in it is often copied when there are other reference types in it.
Use absolute references (e.g. $C$3) instead of relative references (e.g. C3). See related questions for more information about absolute references.
Yes. Cells are referenced in a grid referencing system. Columns are identified by letters and rows are identified by numbers. So, for example, cell D53 would be the cell in column D and row 53.
Named cells are normally used to reference specific cells, so they would be absolute references.
Mixed reference
Absolute references are fixed. Relative addresses are not. You use an absolute reference when you want to move the cell contents without changing the formula.