You can do both.
Some hamsters are adventurous, while some just like things organized.
It's better to keep the food in the food bowl, so the hamster knows where to go if they are hungry.
At the same time, scatter some in the cage, and if your hammy is adventurous, they would collect all the food and bring it to their nest, or store it in the food bowl.
If you want to do something fun, make a pinata for them.
Take some of your hammy's favorite treats and put them in a tissue paper, and make cover it up with it, and then hang it with a string, from the top of the cage.
Watch your hammy stand up, biting the tissue paper to reach the food. It is fun and they do something fun!
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