The word “seven” is punned in the puzzle. Seven is an odd number, since the word “seven” only includes five letters. The word “even”—which is an even number—remains after the letter “s” from the word “seven” has been removed.
The riddle also uses wordplay. The word “even” can refer to both the quantity two and an a condition of equality. Since 4 is even and 4 is the number that remains when the letter “s” from the word “seven” is removed, the word “even” in this context refers to the number 2.
The answer to the question is provided in greater detail below:
“Seven” is a five-letter word.
A strange number is seven.
“Even” is a four-letter word.
Even numbers begin with two.
4, which is even.
The word “even” results when the letter “s” from the word “seven” is removed.
The number seven is therefore the solution to the enigma.