In the following question, select the missing number from the given series.
6 10 9
7 2 13
4 ? 8

Let's check the column-wise or row-wise properties of the matrix.
Let's sum the numbers in each column:

Column 1: 6+7+4=17

Column 3: 9+13+8=30
No clear pattern.

Let's look at the row-wise sum:

Row 1: 6+10+9=25

Row 2: 7+2+13=22

Row 3: 4+x+8=12+x

Let's test an alternative relationship:

Sum of first and third column numbers=middle column function
Row 1: 6+9=15→15−5=10

Row 2: 7+13=20→20÷10=2? Not consistent.

Let's check the row sums pattern again:
Notice that:

Row 1 sum: 25

Row 2 sum: 22
The row sums are decreasing by 3 (25−3=22).
Following this sequence rule, the sum of Row 3 must be 22−3=19.

Therefore:

4+x+8=19
12+x=19
x=19−12=7
Hence, the missing value is 7.