Hello Math-Fun, The idea is to read the decimalization of Pi from left to right and to delete _all_ the read digits with the hereunder rule: - Sum, one by one, the digits you encounter; - When the partial sum is visible immediately to the right of the summed digits, erase the said digits; - Start summing again, from zero. Example: Pi decimalization starts: 3.1.4.1.5.9.2.6.5.3.5.8.9.7.9.3.2.3.8.4.6.2.6.4.3.3.8.3.2.7.9.5.0.2.8.8.4.1.9.7.1.6.9.3.9.9.3.7.5.1.0.5.8.2.0.9.7.4.9.4.4.5.9.2.3.0.7.8.1.6.4.0.6.2.8.6.2.0.8.9.9.8.6.2.8.0.3.4.8.2.5.3.4.2.1.1.7.0.6.7.9... We read from left to right; as 3+1 = 4 we erase the first two digits; we are left with: 4.1.5.9.2.6.5.3.5.8.9.7.9.3.2.3.8.4.6.2.6.4.3.3.8.3.2.7.9.5.0.2.8.8.4.1.9.7.1.6.9.3.9.9.3.7.5.1.0.5.8.2.0.9.7.4.9.4.4.5.9.2.3.0.7.8.1.6.4.0.6.2.8.6.2.0.8.9.9.8.6.2.8.0.3.4.8.2.5.3.4.2.1.1.7.0.6.7.9... We start summing again, from left to right; as 4+1 = 5 we erase the first two digits; we are left with: 5.9.2.6.5.3.5.8.9.7.9.3.2.3.8.4.6.2.6.4.3.3.8.3.2.7.9.5.0.2.8.8.4.1.9.7.1.6.9.3.9.9.3.7.5.1.0.5.8.2.0.9.7.4.9.4.4.5.9.2.3.0.7.8.1.6.4.0.6.2.8.6.2.0.8.9.9.8.6.2.8.0.3.4.8.2.5.3.4.2.1.1.7.0.6.7.9... We start summing again, from left to right; as ... [and here I must confess that I don't have the tools to find the next chunk of digits; the sum is bigger than 100] This erasing technique can be summarized by the size (in digits) of each erased chunk. We would thus have(for Pi): [2,2,...] Best, É. e size of each chunk is the signature of th