let order of tree be p.
case 1 : for internal node :
size of key * #keys + tree ptr * #child pointer <=1024
15(p-1) +5p<=1024
20p<=1039
p<=51.98
p=51
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case 2 :for leaf node
(key pointer +data pointer)(p-1)+ tree pointer <=1024
20(p-1)+5<=1024
20p<=1029
p<=51.98
p=51
------------------------------------------------------------------------------------------------
so in both cases we get 51 so order of tree is 51.