Knowledge of pencils

How far is the pencil written?

The writing distance that can be written in one pencil (HB) is about 50km.
It is an overwhelming long distance and economical compared with other Writing instruments. However, the written load is set to 150g, the core without sharpened, because it is a number under the condition that all writing one (about 172mm), but it is not so realistic.
By the way, with the Spare Leads , the Spare Leads OF 0.5 mm and HB (60mm length) is used all, and the writing line obtained is about 240m.