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Cell referencing
Columns are numbered with letters and rows with numbers. A cell can be specified using a latter and a number.
When cell references are copied (perhaps as part of formulae), the references may be automatically changed in a certain way - this is called relative reference: Eg: The reference A20 used in cell A2, when copied to B2 will automatically be changed to B20.
When such change does not happen, we have absolute reference to a cell. Eg A$20, and $A20 (the former indicating that the row is fixed and the latter fixing the column), $A$20.
Range specification
A:A, A2:A30.
Filtering
Condition specification
“>0”, value.
Counting
COUNTIF(rangeToCheck, condition, rangeToCount). rangeToCount is optional.
COUNTBLANK. COUNT.
Summation
SUMIF, SUM. These have syntax similar to countif and count.
Averaging
AVG(RANGE)
Looking up values
vlookup()