root level has 4 keys for maximum----4
so there will be 5 pointers so 5 child nodes so no. of keys will be 20
so there will be 25 pointers so 25 child nodes so no.of keys 25*4=100
so there will be 125 pointers so 125 child nodes no.of keys 125*4=500
so there will be 625 pointers so 625 child nodes no. of keys 625*4=2500
so total 3124