Question
Explain why $1 \times 2 \times 3 \times 4 \times 5 \times 6 \times 7+5$ is a composite number?
✓
Answer
We can write $1 \times 2 \times 3 \times 4 \times 5 \times 6 \times 7+5$ as
$\Rightarrow 5(1 \times 2 \times 3 \times 4 \times 6 \times 7+1)$
$\Rightarrow 5(1 \times 2 \times 3 \times 4 \times 6 \times 7+1)$
$=5 \times 1009$
Hence we can say that the given number has at least one factor other than $1$ and number itself.$
\Rightarrow(5,1009,1,5045)$
Therefore $1 \times 2 \times 3 \times 4 \times 5 \times 6 \times 7+5$ is a composite number.
$\Rightarrow 5(1 \times 2 \times 3 \times 4 \times 6 \times 7+1)$
$\Rightarrow 5(1 \times 2 \times 3 \times 4 \times 6 \times 7+1)$
$=5 \times 1009$
Hence we can say that the given number has at least one factor other than $1$ and number itself.$
\Rightarrow(5,1009,1,5045)$
Therefore $1 \times 2 \times 3 \times 4 \times 5 \times 6 \times 7+5$ is a composite number.
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