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Write five pairs of prime numbers less than 20 whose sum is divisible by 5.
Solution:
Prime Numbers are the numbers with two factors, 1 and the number itself.
According to the Divisibility Rule of 5, any number ending with 0 or 5 is divisible by 5.
The numbers divisible by 5 are 5, 10, 15, 20, 25, ... (Multiples of 5)
Let's express these numbers as a sum of two prime numbers lesser than 20, that are, 2, 3, 5, 7, 11, 13, 17, 19
a) 5 = 2 + 3
b) 10 = 3 + 7
c) 15 = 2 + 13
d) 20 = 3 + 17
e) 20 = 7 + 13
Therefore, five pairs of Prime Numbers less than 20 whose sum is divisible by 5 are (2, 3), (3, 7), (2, 13), (5, 5), (3, 17), (7, 13)
Write five pairs of prime numbers less than 20 whose sum is divisible by 5.
Summary:
Five pairs of Prime Numbers less than 20 whose sum is divisible by 5 are (2, 3), (3, 7), (2, 13), (5, 5), (3, 17), (7, 13)
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