Title: STACK instructions
Course: Study PrepProg Mathematics

Here are most commonly used commands:

Function | On paper | In Moodle
Multiplication | 2t | 2*t
Division | 2 3  2:3 | 2/3
Power | a^2 | a^2
Square root | 812 | sqrt(812)
Fraction notation |  | 12/5
 | sin(α) | sin(alpha)
 | cos(β) | cos(beta)
 | tan(γ) | tan(gamma)
 | sin^-1(α) | asin(alpha)
pi | π | pi
Natural logarithm | ln() | log(), ln()
a -base logarithm | log_a(x) | lg(x,a)
absolute value | |x| | abs(x), |x|
inequality | ≤ | <=
 | ≥ | >=
 | ≠ | #
and |  | and
or |  | or

•       Dot is a decimal separator.

•       Stack demands precise answers. if you forget multiplication symbol, Stack won´t accept your answer.

•       Remember to mark all calculations. For example, on paper 2t must be written as 2*t in stack.

•       If answer is asked as formula, don´t write numeric values at all.

•       Follow precisely given instructions. Sometimes question have only one way to give answer.

•       Don´t write degree signs or any  units in your answers.

•       Check how stack understands your answer (right variable and so on).

•       If the answer box is bigger than few symbols, you need to give intermediate steps also (although not mentioned separately).

•       Answer all questions before ending exam.

1.      While solving equations, do not write equal sign at the beginning of the row.

2.      Every intermediate step on its own row.

3.      When processing expressions, a new line begins with an equal sign.

Here are some exercises with correct and wrong answers.

Picture 1.Example of power calculation.

Picture 2. Example of the meaning of parentheses in rational functions.

 Here is an example of writing expressions when intermediate steps are needed. In the case of expressions, it is a good idea to write the original expression on the first line, so that the correctness of the solution is constantly checked. For example, in the situation below, the first term is forgotten to put in parentheses, so the next line is no longer the same as the original task and Stack wonders this with a red question mark.

 Picture 3. Parenthesis missing.

In the situation in the following image, the original task is not written first, so Stack compares the written lines with each other. Because they are the same, the solution to the problem seems right before the return. However, the final answer is not the same as the correct solution, so the task is classified as incorrect.

 Picture 4. Missing the original expression.

Picture 5. Solution for correctly calculated equation.