THE Primary Mathematics Standards Edition, which is for grades one to five, is adapted from the Primary Mathematics Project series co-published by Singapore's Marshall Cavendish and the Ministry of Education in 1982.

Marshall Cavendish, a publishing brand under Times Publishing Group in Singapore, worked with SingaporeMath.com - an Oregon-based company which distributes Singapore mathematics textbooks in the United States - to market the books there.

Besides the primary school series, there is also the Earlybird Kindergarten Mathematics Standards Edition, an adaptation of the Earlybird Preschool Mathematics used by kindergarten-age children in Singapore.

The Singapore books needed a little tweaking for the American market - for example, Singapore dollars became US dollars, while 'apples' were used in examples instead of tropical fruits such as rambutans or durians.

Last November, the state of California approved the use of these maths textbooks in schools there.

SingaporeMath.com estimated last year that Singapore books are used by 70,000 students in 700 to 800 schools in the US, mainly in states such as Massachusetts, New Jersey and Wisconsin.

Singapore maths textbooks are used not only in the US, but also in neighbouring countries such as Thailand, Hong Kong, Indonesia and Malaysia.