Priscilla Ng's answer to mary's Primary 4 Maths Singapore question.
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The 2 questions used the same concept to solve.
Both items in comparison have same number being taken away. Hence, their difference in their numbers before and after the change remains the same.
Notice the model drawing, the shorten bars in the 'After' model are cut in the front so that we can compare it to the 'Before' model and hence change the big units in the 'Before' model to small units accordingly.
Both items in comparison have same number being taken away. Hence, their difference in their numbers before and after the change remains the same.
Notice the model drawing, the shorten bars in the 'After' model are cut in the front so that we can compare it to the 'Before' model and hence change the big units in the 'Before' model to small units accordingly.
Date Posted:
1 year ago
Thank you
Hi, may i check why 1 unit is further divided to 3 units for both qns? Thank you
As mentioned in my explanation for the solution, the difference in the 2 items in comparison did not change as in 'Before' and 'After'. This is known as 'Difference Unchanged' concept.
Q9 and Q10 happened to be the same for one Big Unit = 3 Small Units.
Comparing the Long Bar to Short Bar in 'Before' and 'After' Model, the difference in the length did not change as indicated with the blue lines, we can see that in Q9, 2 Big Units = 6 Small Units and in Q10, 3 Big Units = 9 Small Units. That is the reason for 1 Big Unit is cut into 3 Small Units.
Q9 and Q10 happened to be the same for one Big Unit = 3 Small Units.
Comparing the Long Bar to Short Bar in 'Before' and 'After' Model, the difference in the length did not change as indicated with the blue lines, we can see that in Q9, 2 Big Units = 6 Small Units and in Q10, 3 Big Units = 9 Small Units. That is the reason for 1 Big Unit is cut into 3 Small Units.
Ok, thank you
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