Fun with mathematics

Test your children's problem-solving skills - and your own - with this four-part weekly series of maths questions targeted at upper primary students. The worked solutions and advice are provided by Assistant Professor Lee Ngan Hoe, Assistant Head (Mathematics Education - Teaching), Mathematics & Mathematics Education Academic Group, at the National Institute of Education, Nanyang Technological University.


•Try to understand the question first. What is the problem about? What information has been given? What does it mean? What are you supposed to find? What happens to a number when its decimal point is shifted to the right by one place? What does it mean to say "the difference between the original number and this new number is 7.29"?

•Work out a plan to solve the problem. What can you try to do? How can you represent the information? Are there relationships among the pieces of information contained in the problem?

•Try to make sense of the answer. How comfortable are you with your answer? Is there a way to check it? What have you learnt from solving this problem?

•Overall advice: Be systematic when solving an unfamiliar problem. Do not focus too much on whether you can get the answer. Try to understand the problem and draw on your mathematics knowledge to make sense of it. It is helpful to represent a problem in diagrams to look for relationships. Avoid being too quick to accept an answer to a problem. Try to find a way to check your answer.


•Be a partner on this problem-solving journey. Do not be too anxious to lead as that may block the child's view. Encourage the child and give a helpful nudge along the way.

•Discourage the child from making pre-emptive judgments on whether he or she can solve the problem. Ask the child questions about the context of the problem to help him or her understand it. Act out how you would attempt to solve the problem.

•Help the child activate the necessary maths knowledge and skills to solve the problem. Encourage the child to look for familiar words in the problem context which might trigger the necessary skills. Maths skills needed for this problem include decimals and place values, multiplying numbers with decimals by 10, and dividing numbers with decimals by a single-digit number.

•Children may be hasty in accepting an answer, especially if the journey has been challenging. Encourage children to check their work and make sense of their answer.



Leonard took four mathematics tests. The average score of the four tests was 86. His lowest score was 17 marks lower than his highest score. His lowest score was no less than 75. Which of the following cannot be his scores for the other two tests?

1. 85, 90

2. 83, 92

3. 84, 89

4. 88,91

The answer to Question 2 can be found online at It will also be published in the Education pages of The Straits Times next Monday.

Brought to you by Marshall Cavendish Education

A version of this article appeared in the print edition of The Straits Times on February 20, 2017, with the headline 'Fun with mathematics'. Print Edition | Subscribe