This is actually not uncommon. Today most academic exam from Primary school to PhD qualify exam in US are all focused on testing muscle memory performances.

"I was slow. I was very slow and I was not quick at doing arithmetic. I remember particularly, when I was in Canada during the war years when I was about eight. The teacher there, she had little mental tests and you had to do a mental arithmetic – add seven, multiply by three, subtract four. I would simply lose track very quickly. She thought I was very stupid and decided to move me down."