J's answer to Opportunity's Primary 5 Maths Rate & Ratio Singapore question.
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① The sum of its two smallest factors is 3.
Any number always has the smallest factor of 1. (Eg. 400 = 400 × 1)
The only possible combination that gives a sum of 3, is 2 and 1 (2 + 1 = 3)
So this 2-digit number is divisible by 2, which means it is an even number.
②The sum of its two largest factors is 33.
Now recall that a number's largest factor is the number itself. (Eg. 100 = 100 x 1).
③ Since the next smallest factor is 2, the number can be divided by 2 to get half its value.
So the number = 2 × (½ of the number) . This tells you that the second largest factor is half of the number. i.e if the number is 2 units , then second largest factor is 1 unit.
Total = 3 units = 33
So 1 unit = 33 ÷ 3 = 11
2 units = 22
The number is 22.
Factors of 22 : 1, 2, 11, 22
Any number always has the smallest factor of 1. (Eg. 400 = 400 × 1)
The only possible combination that gives a sum of 3, is 2 and 1 (2 + 1 = 3)
So this 2-digit number is divisible by 2, which means it is an even number.
②The sum of its two largest factors is 33.
Now recall that a number's largest factor is the number itself. (Eg. 100 = 100 x 1).
③ Since the next smallest factor is 2, the number can be divided by 2 to get half its value.
So the number = 2 × (½ of the number) . This tells you that the second largest factor is half of the number. i.e if the number is 2 units , then second largest factor is 1 unit.
Total = 3 units = 33
So 1 unit = 33 ÷ 3 = 11
2 units = 22
The number is 22.
Factors of 22 : 1, 2, 11, 22
Date Posted:
3 years ago
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