This site

http://www.recordholders.org/en/list/mental-calculation-rankings.html

lists 66 people who have solved all ten correct in less than 380 seconds (therefore with an average of less than 38 seconds per task).

The Memoriad official site lists 57 people who have solved all correct in less than 380 seconds (6 minutes and 20 seconds).

http://www.memoriad.com/index.asp?s=kategoriler&b=kategori-detay&kategoriid=32af8531c0f239cd0fa827292ce01e7a&lang=EN#results

But not all of them coincide. So, probably around 80 people have solved all these 10 tasks correct in a competition environment. And I would estimate around 100 more people can get below that 380’’ in their home environment (since competitions actually entail an additional pressure to perform flawlessly)

But what about a person who does 7 minutes(420’’ all 10 tasks correctly) ? I think that person can definitely solve 1 correct in under 38 seconds, because 1 task is always easier and less tiresome than 10.

On the main topic, I have been in many competitions and the fastest person on additions is definitely Mrs. Lee from South Korea. She has the world record with 10 additions correct in 100 seconds. I have seen her with my own eyes, that she can solve correctly 1 of such addition tasks in around 9 seconds. She does 3 numbers simultaneously, so she needs around 3 seconds for each 3-digit highlighted column, and this time includes typing the result as well, besides calculating.

The final 1-digit column she does it together with the 3-digit column, so essentially she is adding 4-digit numbers in the end. To sum up, she does the 3-digit column first, then the middle 3-digit column and finally the 4-digit column, which gives a 5 digit partial result, and 11 digits for the total answer (3 first digits + 3 middle digits + 5 last digits). All this done from right to left of course.

I agree with the initial poster. Hard work is not enough. There has to be some kind of talent, and it’s definitely not 1% talent/ 99%hard work as people use to say. In these types of skills, talent is at least 30-40% but of course this cannot be quantified easily.

Regards,

Nodas