Find the number of different prime factors of 6440
Choose the correct choice.
A) 4
B) 2
C) 3
D) 5
E) 6

Rationale: "explanation : l . c . m of 6440 = 2 x 2 x 2 x 5 x 7 x 23 2 , 5 , 7,23 number of different prime factors is 4 . answer : option a"
Answer: A