Count the number of characters in a string

LEN(text)

Return the serial number of the current date

=TODAY()

Sum (add) values in a range that meet a single criteria.

SUMIF(range,criteria,[sum range])

Sum (add) values together.

=SUM(number1,number2,…)

Sum (add) values in a range that meet multiple specific criteria.

SUMIFS(sum_range, criteria_range1, criteria1, [criteria_range2, criteria2], ...)

Return the logical value TRUE if a cell contains the #N/A error

=ISBLANK(value)

Extract characters from the beginning or end of a string.

LEFT(text, [num_chars]), LEFTB(text, [num_bytes])

RIGHT(text, [num_chars]), RIGHTB(text, [num_bytes])

Return the number of days between two dates

=DAYS(end_date,start_date)

Return the logical value TRUE for any error type except the #N/A error.

=ISERR(value)

Return a random number between 0 and 1

=RAND()

Return the most common value in a data set

=MODE.SNGL(number1, [number2], ...)

Return the logical value TRUE if a cell is blank or empty

=ISBLANK(value)

Return the year, month or day component of a date

=YEAR(serial_number), =MONTH(serial_number), =DAY(serial_number)

Evaluate and return the contents of a reference specified by a text string

=INDIRECT(ref_text, [a1])

Extract characters from within a text string.

MID(text, start_num, num_chars), MIDB(text, start_num, num_bytes)

Return the serial number of the current date and time

=NOW()

Return the logical value TRUE if the cell contains any value that is not text.

=ISNONTEXT(value)