Depending on where you study, it is
BIDMAS = Bracket, Index, Division, Multiplication, Addition and Subtraction.
or
PEMDAS = Parentheses, Exponent, Multiplication, Division, Addition and Subtraction.
Actually, these should be BI(DM)(AS) and PE(MD)(AS) since D and M are treated as equals and evaluated left to right, as are A and S.
There is no operation for a single number and so there can be no order of operation.
There are 6 pats in an operation order
order of operation
33.8
Order of battle Swatow Operation happened in 1939.
Operation Chahar order of battle happened in 1937.
Operation Brevity order of battle happened in 1941.
They must follow the order of operation because if they don't, they will not get the same answer.
operation order
operation order
PEMDASParenthesesExponentsMultiplicationDivisionAdditionSubtractionorPleaseExsuseMyDearAuntSally
ParenthesesExponentsMultiplicationDivisionAdditionSubtraction