This article focuses on solving a group of problem sums in PSLE Math whereby the value of a certain variable remains the same whether in the "Before" or "After" scenario. The strategies shared here are regularly used in schools and tuition centres as they can be applied across different topics with part-whole concepts like Decimals, Ratio, Fractions, Percentage and Whole Numbers.

In the previous article, I have shown you two strategies on Same Difference and Same Total. Today, I will continue to share with you two more key strategies that are often tested in school-based examinations or PSLE Math – Same Identity and Unchanged Variable.

This strategy is a non-routine heuristic that all pupils learn in primary schools. Many pupils learn how to use this strategy as early as when they were in primary two. In fact, the concept of working backwards is useful in many aspects of life, not just in solving Math problem sums.

Though easy to apply, it might not be easy to use Guess-and-Check to solve questions whereby numbers involved are big. A student might need to make many guesses before he can successfully “guess” the correct answer. A more efficient strategy, Assumption, was taught by many Math teachers and tutors to replace the conventional Guess-and-Check method.