# Counting number

What is the smallest counting number divisible by 2,5,7,8 and 15?

Result

x =  840

#### Solution:

$2 \ ... \ prime number \ \\ 5 \ ... \ prime number \ \\ 7 \ ... \ prime number \ \\ 8=2^3 \ \\ 15=3 \cdot 5 \ \\ LCM(2, 5, 7, 8, 15)=2^3 \cdot 3 \cdot 5 \cdot 7=840 \ \\ \ \\ x=LCM(2,5,7,8,15)=840$

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