Try to follow these guidelines: - 1-mark question to be done within 1minute, 2-mark question within 2 mins, so as to eke out time for 3-mark and above questions - Apply RSVP for questions involving geometry and diagrams/tables/graphs/piecharts - Draw models or do story-boarding when encountering word problems with fraction, ratio, percentage
Chang's Math blog
Compilation of all things math --- questions obtained via students' consultation, related math sites. * Do also check out my EduTech contributions at go.gov.sg/changcl
Friday, July 24, 2026
Thursday, July 23, 2026
P5 order of operations
Most people get this wrong on the first try.
72 ÷ (8 + 4) × 6 − 9
____
Why is it so?
One reason is based on the misconception that multiplication has higher ranking than division.
Another is when people have only a partial understanding of order of operations. While they know that / and x have the same rank, and ought to operate from left to right, they are nevertheless affected by a phenomenon I coined as “the luring of numbers”: given that 12x6=72, and 72/72 will “conveniently” yield 1 for the result of the first 4 numbers (in turn resulting in a wrong final answer of -8) , when it ought to be 36 (where final answer should be 27)
Wednesday, July 22, 2026
P5 numbers, multiples, decimals, area of triangle, perimeter, pattern
Tuesday, July 21, 2026
Monday, July 20, 2026
Sec3 Sec4 Geometry (cyclic quad and angle at centre = 2x angle at circumference)
P6 circles
_______ my solution 5r = 66-3x2 = 60 r =60/5=12 (a) Breadth of garden= (2+12)x2=28 m (b) area of path = 2x14 + 5 x 1/4 x 3.14 x (14x14 - 12x12) = 28 + 5x40.82 = 232.1 m2
Saturday, July 18, 2026
Friday, July 17, 2026
Thursday, July 16, 2026
Numbers in relation to our lifetime ( Significance of numbers in our lives )
How many moments (seconds) have we lived? 🤔
For a centenarian, his/her heart would have beaten 3 153 600 000 times (read as "That number is three billion, one hundred fifty-three million, six hundred thousand.) ie. 3 billion times in 1 lifetime.
Internet speed is in the range of 500 Mbps (500 000 000 bits per second) or 10 Gbps (10 000 000 000 bits per second)
