For calculated questions please refer to Creating a Simple Calculated Question. For more in depth instructions on numerical questions, see

Click any image below to enlarge

Create a question by selecting  the drop down for ‘question bank’ and then select ‘questions’

On the next page select the ‘create a new question’ button

Select 'numerical' from the list then click 'Add'

Select which category you want the question to be added to in the question bank

Enter a question name, this will not be shown to students but should help identify the question for you

See Using the Equations Editor to Insert Mathematical Equations for more information.

This sets the maximum mark for this question.

Enter the correct answer and select a percentage it will be worth (if multiple answers are entered this must add up to 100%)

You can add feedback  as well to help students understand where they went wrong or why they were correct.

Click save changes to add the question to category

You will then be displayed with your question and other questions in that category. You can click the magnifying glass icon 

For information on adding questions to your quiz see the 'Adding Questions To Your Quiz' section of Creating Questions / Building Your Quiz.

There are also options for allowing students to choose a 'unit' to answer with, please see here for more information.