She correctly answered six out of 10 tasks - each involving the addition of 10 rows of 10-digit numbers - at a mathematical olympiad on May 30. The score is a new Singapore record. The 5min 17sec she took was also the fastest among 345 other contestants, most of whom were older than her.
By comparison, the world record holder is Mr Alberto Coto of Spain, who in 2008 got 10 out of 10 correct answers in 4min 26sec. He was 38 then.
As an additional sweetener, Cherlyn made it into the Singapore Book of Records as one of its youngest individual record holders. The youngest is a 23-month-old girl who swam 100m unassisted.
Cherlyn's remarkable feat is the first visible result of her parents' grand plan to develop her intelligence.
When she was three, her father, marketing manager Brandon Lee, began buying her kindergarten-level assessment books.
Then, in May last year, Mr Lee, 37, watched a
television show where he was introduced to CMA Mental Arithmetic school, which combines the millennia-old abacus as a counting instrument and the system of 'Image Memory' to allow quick and sharp number calculations.
First opened in December 2005, CMA has expanded from its Yishun headquarters to 17 other centres across the island, with 6,000 children having tried its programme.
Mr Lee decided to enrol Cherlyn in the school instead of music and dance classes.
From then on, either he or his wife, Ms Margaret Tan, 34, would spend two hours a day - weekends and public holidays included - to help Cherlyn with the coursework.
'When kids get attention, their interest grows for these things,' said Mr Lee.
Desire and motivation were certainly needed, as the curriculum, meant for children aged 31/2 to 13, was not easy.
To finish the 23-level course, students had to learn on a physical abacus, move on to an imaginary one, and then progress to using a 'two hand, four finger' method to calculate long arithmetic problems in their heads.
The final stretch was the hardest, involving problems which are read aloud, rather than on paper.
Perhaps as a sign of Cherlyn's impending achievement, she began to finish three to four 60-page practice books every week, when other children managed only 10 to 20 pages.
Furthermore, Cherlyn, who turns six on June 21, has been in the school for only 11 months and is almost done with the course. Others usually take five to seven years, said CMA chief executive Tay Shy Ching.
According to her parents, no one needs to make Cherlyn hit the books. 'Sometimes, I say she should sleep, but she will say: 'I want to do Chinese or English',' said Mr Lee. 'We don't force her.' The reticent child was firm about her favourite thing - 'numbers' - and named 'scientist' as a career aspiration.
The Lees intend to carry on with their daughter's intellectual development, eyeing vocabulary and speed reading as important skills to master.
But when the schooling is done, the real-world lessons come in. 'We will begin to teach her how to become a good person, a moral child,' said Mr Lee.
Their second child, three-year-old Xavier Lee, has yet to follow in his sister's footsteps.
As for Mr Coto's world record, Mr Lee feels it is not out of the question, but it is not a priority. 'Maybe we can try, but we don't set it as a target.'
