In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[EX Q]: Most volcanoes erupt for _ to four weeks and then rest.
[EX A]: three

[EX Q]: Screws provide at least _ times the holding power of nails.
[EX A]: seven

[EX Q]: Rocks are of _ kinds, igneous and sedimentary.
[EX A]:
two