If

=IF(test, then, else)
=IF(EQ(A1, "paid"), "true", "false")

Comparators

=EQ(a,b)
=NE(a,b)
=GT(a,b)
=GTE(a,b)
=LT(a,b)
=LTE(a,b)

Math

=POW(2, 32)   # 2^32
=SIN() ACOS() etc
=CEILING(n,sig,mode)
=FLOOR(n,sig,mode)
=INT(n)

=SUM(range)

=SUMIF(range, criteria, sum_range)
=SUMIF(A1:A5, ">300", B1:B5)          # if A# is >300, use B#

Core

=TO_DATE(number)

Vlook

=VLOOKUP(value, range, column_index)