Final answer:
It is difficult to provide an exact number of satchel charges required to destroy a stone high external, as it depends on the strength of the stone and the explosive power of the charges.
Step-by-step explanation:
In order to determine how many satchel charges it takes to destroy a stone high external, we need to consider the amount of force required to break the stone. Stone is a hard material, and its strength can vary depending on the type and density of the stone. To break a stone, we need to apply enough force to exceed its ultimate tensile strength or compressive strength.
Without specific information about the strength of the stone and the explosive power of a satchel charge, it is difficult to give a precise answer. However, based on general knowledge of stone strength and the power of explosives, it would likely take multiple satchel charges to destroy a stone high external.
For example, if a stone high external is made of a strong granite stone, it may require several satchel charges to break through the stone. On the other hand, if the stone is a softer limestone, it may break with fewer satchel charges.