The bottom row is growing by two (arithmetic sequence) by the time it gets to case 100 the bottom row will have 3 + 2(100-1) objects, which is 201.
This means that in case 100 the rows should follow the following pattern beginning with the first row all the way up to the last row: (1 +3 +...+201)
To figure out the summation one can use the formula (n(a1+an))/2
To figure out n: 201=1 +2(n-1) n=101 So the sum would be (101(1+201))/2 10,201
For detailed explanations on arithmetic sequences and the formulas check out this website: