Question

What four factors were used to create this product game board 9,15,18,21,30,35,36,42,49

Answer 1

3,5,6,7 All of the numbers are created by multiplying these four numbers.

Answer 2

To see what are the factors use, we write each of the numbers, as product of prime factors:

$9= 3 \cdot 3\\\\ 15=3 \cdot 5\\\\ 18= 2 \cdot 9 = 2 \cdot 3 \cdot3\\\\21= 3\cdot 7\\\\30=3 \cdot10=3 \cdot 2 \cdot 5\\\\35=5 \cdot7\\\\36=6\cdot6=2\cdot3\cdot2\cdot3\\\\42=6\cdot7=2\cdot3\cdot7\\\\49=7\cdot7$

As we can see, the 4 factors used to produce the numbers in the list are {2, 3, 5, 7}


Answer:  {2, 3, 5, 7}