Shawn's answer to Jonathan's Primary 6 Maths Singapore question.
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If you want to solve using algebra and simultaneous equations.
Another way to solve this is to use logic.
If after putting 4 per box, you’re left with 32 (which can be divided by 4 exactly), it means that the number of lollipops you have is in multiples of 4.
After putting 7 per box, you last box only has 3 lollipops. If you have another 4 more lollipops, you can put all 7 per box equally for all the boxes. Which means that a multiple of 7 - 4 is equal to a multiple of 4
By knowing these 2 statements, you can compare the multiples of 4 and 7. 4x20=80, 7x12=84
84-4=80 which is also a multiple of 4 which fits the statements. Hence the number of lollipops you have is 80. The number of boxes you have is 12.
Another way to solve this is to use logic.
If after putting 4 per box, you’re left with 32 (which can be divided by 4 exactly), it means that the number of lollipops you have is in multiples of 4.
After putting 7 per box, you last box only has 3 lollipops. If you have another 4 more lollipops, you can put all 7 per box equally for all the boxes. Which means that a multiple of 7 - 4 is equal to a multiple of 4
By knowing these 2 statements, you can compare the multiples of 4 and 7. 4x20=80, 7x12=84
84-4=80 which is also a multiple of 4 which fits the statements. Hence the number of lollipops you have is 80. The number of boxes you have is 12.
Date Posted:
2 years ago
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