What signifies a "number without a fractional part"?

The term "number without a fractional part" specifically refers to whole numbers. Whole numbers include all non-negative integers starting from zero and moving upwards (0, 1, 2, 3, ...). These numbers do not possess any decimal or fractional components; they are complete units.

In contrast, the other choices involve fractional or mixed parts. A proper fraction is less than one and has a numerator that is smaller than its denominator. An improper fraction, however, has a numerator that is greater than or equal to its denominator and can also represent whole numbers, but it explicitly contains fractions. A mixed number consists of a whole number combined with a proper fraction, thus also containing a fractional part. Therefore, the characteristic of being a "number without a fractional part" is uniquely fulfilled by whole numbers.