The students who evaluate an expression must follow a precise order or nomenclature. The assumption is that only one can be the result. Turns out, if the students do not follow step by step the order the result will be different and probably wrong.

The acronym of this is the P.E. MD.AS:

P. Parenthesis (which are a group of symbols):
E. Exponents
MD. Multiplication and/or divisions are managed simultaneously.
AS. Addition and/or Subtraction are managed simultaneously.

First: solve the expressions inside the brackets ( they could be (-) or [-] or {-})

\(25 \times 4 \div \bigl\{[25-18+3] + [7 \times 8] \times [4 \times (18 + \sqrt{16})^2]\bigl\}\)

Second: evaluation of the elements raised to the power or that have exponents

Third: perform divisions and multiplications. Usually does not matter from left to right or the reverse

Fourth: perform addition and subtractions. Usually does not matter from left to right or the reverse