Question

what is the least common multiple of 3 and 5?
1
8
15
30

Explanation:

Step1: Recall LCM of coprime numbers

For two coprime numbers (numbers with GCD 1), the LCM is their product. 3 and 5 are coprime (GCD(3,5)=1).

Step2: Calculate product of 3 and 5

Multiply 3 and 5: $3\times5 = 15$. Check multiples: Multiples of 3: 3, 6, 9, 12, 15, ...; Multiples of 5: 5, 10, 15, ... The smallest common multiple is 15.

Answer:

The option with 15 (the left - bottom option with the number 15)