Question

Four prime numbers are written in ascending order. The product of the first 3 numbers is 105. The product of the last 3 is 385. Find the second number *

Answer 1

Let the numbers be a,b,c and d.

abc=105

bcd=385

HCF(abc,bcd) = bc

since a and d are prime.

HCF(105,385) = 35 = 5*7

The second number is 5.