Bunuel
Tough and Tricky questions: Number Properties.
What is the sum of the different positive prime factors of 1092?
A. 5
B. 12
C. 20
D. 25
E. 27
Kudos for a correct solution. Official Solution:What is the sum of the different positive prime factors of 1092?A. 5
B. 12
C. 20
D. 25
E. 27
The question asks for the sum of the
different prime factors of 1092.
The first step is to find the prime factorization of 1092. Since the last two digits of 1092 are divisible by 4 (\(92 = 80 + 12 = 4 \times 23\)), we can start by dividing 1092 by 4, giving us \(1092 \div 4 = 273\). Since 4 is equal to \(2 \times 2\), 1092 has two factors of 2.
Now, note that the digits of 273 add up to 12, which means that 3 is one of its factors: \(273 \div 3 = 91\).
The prime factors of 91 are 7 and 13 (there is no easy divisibility rule for 7).
So the prime factorization of 1092 is: \(1092 = 2 \times 2 \times 3 \times 7 \times 13\).
Now take the sum of the
different factors: \(2 + 3 + 7 + 13 = 25\).
Answer: D