Riddles with matrices

Puzzles, riddles, brain teasers, conundrums, logic questions in pictures. Here all tasks are presented in the form of various matrices. Most often these are rectangular matrices that have external rows and columns. In these logic puzzles, brain teasers and conundrums, the columns and rows affect the contents of the matrices. To check your answer, click on the «Answer» button located below the task. After this, the correct answer and explanations will appear. Below you can select other questions on this topic. Typically each topic has 20 questions or more. At the same time, the complexity of logical problems gradually increases. First there will be easy questions, then medium, then difficult. Try to complete tasks as quickly as possible.
Question - 19
In this challenging logic puzzle-conundrum you need to find the relationship between external and internal numbers. Number of external numbers = 8, number of internal numbers = 16. What number can replace the question mark? Select one answer option from those shown below.
Correct answer = 4.
This is where the internal numbers in a column or row are added. The total amount is a two-digit number, that is, the amount consists of two digits. We sum these two digits to obtain an external number. Below is an example of addition in a string. The same goes for columns.
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