Optimus Prime!
Number Theory
Level
2
There are four prime numbers written in ascending order. The product of the first three is 385 and that of the last three is 1001. The last number is :
13
19
17
11
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1 solution
the product of the first 3 numbers is 385 means its divisible by 5, since all of them are prime, one of them must be 5. that means they could either (2,3,5),(3,5,7),(5,7,x) where x is a prime > 7. 2 3 5 is not 385 nor 3 5 7 which leaves us to find x by dividing 385/(5*7) = 11. the last three are (7, 11 , y) where y = 1001/(7 /times 11) => y = 13.
sorry for the bad formatting.