Units of measurement, Titles.
a number and a unit
A number that is divisible by both 3 and 7 must be a multiple of their least common multiple, which is 21. Therefore, any number that is a multiple of 21 will be divisible by both 3 and 7. Examples of such numbers include 21, 42, 63, 84, and so on.
Yes, you MUST.
The value of the measurement and the units used.
The unit of measurement
the unit of mesurement
Velocity is a vector quantity.
A measurement includes both a number and a unit to provide a quantitative value and context for what is being measured. The number indicates the amount or quantity being measured, while the unit specifies the scale or magnitude of the measurement. Without both components, the measurement lacks clarity and may be misunderstood or misinterpreted.
Units of measurement, Titles.
Intervals and units of measurement
a number and a unit
A unit of measurement, a number indicating the quantity, and a scale or reference to provide context.
The measurement units and the degree of precision (significant figures or margin of error).
15 Electrons. A charge-less (neutral) atom must have an equal number of both protons and electrons, otherwise it becomes an ion.
Probability is a numerical value and there must bea number, not just include one.
Density is mass/Volume so you must include the units of measurement. For mass, these may be grams or kilograms (or, in countries still using the Imperial system, pounds!). Similarly there are measures for volume. If these were not given it would not be possible to tell whether the density was given in grams per cm3 or pounds per cubic foot.