5a)
i> no digits repeated range 5000-6000
so 5xxx r da possibilities, 1,2,3,4,5,6 5 cannot b used
remaining ones 5P3 as arrangement matters 4 numbers.
ii> repeated digits all num frm 1-6 cn b used
5xxx so 5(6c1)(6c1)(6c1)
so 6*6*6 num cn b formed dat is 63