Question

Find the product of all prime numbers between 1 and 20

• A. 9699645
• B. 9699690
• C. 9699680
• D. 9699670
• E. 9699660

Answer 1

The correct option is B 9699690

Option (b)

Go by elimination. Option a is eliminated because the product of prime numbers 2,5 is $2\times 5=10$, which should yield one zero

As 3 is a factor of the product, check which of the remaining options are a multiple of 3. only option (b) and option (e) are both factors of 3.

Checking for 7 and 13.Sum of triplets at odd places-sum of triplets at even places=0 in option (b). Hence, this is the answer.