Question

Show that $11 \times 19 \times 23 + 3 \times 11$ is not a prime number.

Answer 1

Factor out the common term $11$ from the expression:

$11 \times 19 \times 23 + 3 \times 11 = 11(19 \times 23 + 3)$

Now simplify the expression inside the parentheses:

$19 \times 23 = 437$

$437 + 3 = 440$

Thus, the expression becomes:

$11 \times 440 = 4840$

Since $4840$ is divisible by $11$, it is not a prime number.