Question

2.
Why does a measurement need both a 'number' and a unit for its complete
specification?
Why is a foot step, or a hand span, not used as a standard unit ​

Answer 1

Standard unit of measuring length is called meter. ... But hand span, forearm length and foot step cannot be used as standard units measurements because their length is not the same for all the persons. The length of hand-span, forearm-length and foot step of different persons is different. It varies from person to person.

Explanation:

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