Contour values are _____________ multiples of the contour interval.

• A. Integral or whole number
• B. Fractional values
• C. Decimal multiples
• D. Irrational numbers

Answer: (A)

Contour values come in equal steps defined by the contour interval. Starting from a reference elevation, each higher contour line lies at an elevation that is the reference plus an integer number of these fixed steps. For example, with a base of 100 m and a contour interval of 20 m, the contour values are 100 m, 120 m, 140 m, 160 m, and so on. These are integral multiples of the interval because you can write each value as base + n times the interval, where n is an integer. Fractional, decimal (non-integer), or irrational multipliers don’t fit the fixed-step pattern of contour lines.