Keegan and jeff did some research and found that there are approximately 7,492,000,000,000,000,000 grains of sand on earth. jeff says that this is about 7x10 to the 15th power grains of sand. keegan says this is about 7x10 to the 18th power grains of sand. a. how might jeff have determined his estimate? how might keegan have determined his estimate?
b. who’s estimate, jeff or keegan’s, is more logical, explain

help me pls :’(