a[0,0] = 1
a[0,1] = 2
a[0,2] = 3
a[1,0] = 4
a[1,1] = 5
a[1,2] = 6


Element 0 = 1
Element 1 = 2
Element 2 = 3
Element 3 = 4
Element 4 = 5
Element 5 = 6


First method:  the sum is: 21
Second method: The sum is: 21