Mathematics is the most popular subject among students here - at least when it comes to taking extra classes.

Maths ranked as the top subject for tuition classes among both primary and secondary school students, a survey here has found.

It showed that maths was one of the subjects for tuition in 73.5 per cent of households with primary school-going children. Coming close behind maths was English (72.4 per cent), while Chinese was a distant third (43.6 per cent).

For secondary school students, 65.7 per cent had extra help with elementary mathematics, the survey by The Straits Times and Nexus Link showed. English came in second (49.1 per cent) and additional mathematics ranked third (25.9 per cent).

The choice of subjects for tuition is not surprising, said experts and parents, who noted that these particular subjects are seen as essential for academic advancement.

Associate Professor Jason Tan, an education policy expert at the National Institute of Education, said subjects such as maths and an international language like English are the most in demand for tuition as they are "necessary for advancement in the education systems".

The difficulty of maths, especially at higher levels, also means that parents have a hard time coaching their children in the subject, said tutors and parents.

Full-time tutor Penny Chuah, 25, who provides English, Chinese and maths tuition for pre-school and primary school children, pointed out that "when it comes to maths, most parents would have lost touch with what they had learnt in school".

Tutors and parents noted that syllabuses have changed over the years, and agreed that the subject gets tougher as children move up to secondary school.

Ms Alicia Cheong, 32, who co-founded education centre Beautyful Minds and who has been giving maths tuition for a decade, said parents can still supervise their children at the pre-school level, where maths problems are relatively simple.

"But at the higher levels, they have to deal with abstract concepts and might have to 'outsource' the coaching to a tutor," she said.

In addition, the poll found that, in the earlier years, at the pre-school level, children are likely to need more help with English instead.

About seven in 10 families send their pre-schoolers for tuition in English. Maths came next (38.6 per cent), followed closely by Chinese (34.1 per cent).

Over the past year, Madam Dana Loh, 36, has spent about $350 a month sending her six-year-old daughter, Natalie, who is a K2 pupil, for weekly tuition in both English and Chinese. She has another daughter, aged two.

Madam Loh, who is in the marketing line, feels a strong foundation in English is essential if her child is to do well in primary school, or at least "keep up with the curriculum".

Several parents, however, were surprised that the Mother Tongue languages, such as Chinese, did not rank among the most sought-after tuition subjects in the survey.

Nurse Judy Quah, 47, and her civil servant husband, 53, spend $1,800 a month on tuition for two of their four children - a son in Primary 3 and a daughter in Secondary 1. More than half of the amount goes towards Chinese tuition.

Ms Quah, like many other parents, finds it hard to help her children in Chinese as they do not use the language at home.

"I want my kids to pass the subject," she said. "So I have to send them for extra classes - I don't have a choice."