In the store, there is a promotion: for every purchase of 5 items for 100 rubles each, one item is a gift. If buyers bring 42 items, how many gifts will they receive?

The promotion states that for every 5 items purchased, one is a gift. We need to find out how many sets of 5 items are there in 42 items. We can do this by dividing 42 by 5: $$42 \div 5 = 8$$ with a remainder of 2. This means that 8 sets of 5 items are purchased, and each set earns 1 gift. Therefore, the buyers will receive 8 gifts.

Answer: 8