Evaluate the following double summations:

a$){\displaystyle \underset{j=0}{\overset{5}{}}}{\displaystyle \underset{k=0}{\overset{10}{}}}m=$

b$){\displaystyle \underset{j=0}{\overset{5}{}}}{\displaystyle \underset{k=0}{\overset{10}{}}}k=$

c$){\displaystyle \underset{?}{\overset{?}{}}}]=[0$

d$){\displaystyle \underset{j=0}{\overset{5}{}}}{\displaystyle \underset{k=0}{\overset{10}{}}}j**k=$

e$){\displaystyle \underset{j=0}{\overset{5}{}}}{\displaystyle \underset{k=0}{\overset{10}{}}}(j+k)=$