@jonson She's calculating 8,645,392,175 squared. Each row below the upper line is the product of 8,645,392,175 multiplied by the next digit to the left of the previous digit: (8,645,392,175 * 5) + (8,645,392,175 * 70) + (8,645,392,175 * 100) + ... The number below the lower line is the result.
(8,645,392,175 * 5) + (8,645,392,175 * 70) + (8,645,392,175 * 100) + ...
The number below the lower line is the result.