1. Come up with five different natural numbers whose product is 1000.
Solution. Note that $1000=10 \cdot 10 \cdot 10=2 \cdot 5 \cdot 2 \cdot 5 \cdot 2 \cdot 5=1 \cdot 2 \cdot 5 \cdot(2 \cdot 2) \cdot(5 \cdot 5)=1 \cdot 2 \cdot 5 \cdot 4 \cdot 25$. Answer: $1,2,4,5,25$.