Chronological reduction of a map 🗺 using short steps

This is typically given as a representative fraction (e.g., 1:50,000) or a graphic scale bar.

For a reduction, the new scale's denominator will be larger than the original scale's denominator (e.g., reducing from 1:50,000 to 1:100,000).

This is the ratio of the original scale's denominator to the new scale's denominator.
For example, if reducing from 1:50,000 to 1:100,000, the reduction factor is:

Multiply every distance on the original map by this factor to get the corresponding distance on the reduced map. For instance, a 4 cm line on the original map would become $4 \text{ cm} \times \frac{1}{2} = 2 \text{ cm}$ on the reduced map.