Question

The product of a non-zero whole number and its predecessor is always:

• A. an even number
• B. an odd number
• C. a prime number
• D. divisible by $3$

Answer 1

The correct option is A an even number

Set of whole numbers$=\{0,1,2,3,4,5\cdots \}$
Set of non-zero whole numbers$=\{1,2,3,4,5,6\cdots \}$
Let us take some examples which follow the above condition
$1)$ Whole number $=7$
Predecessor = 6
Product $=7\times 6=42$ i.e. even number
$2)$ Whole number $=50$
Predecessor = 49
Product $=49\times 50=2450$ i.e. again an even number.
Therefore product of non-zero whole number and its predecessor is always an even number.