Working with whole numbers can be really fun! But it’s important to be careful about some easy mistakes. Here are a few to watch out for:

1. Ignoring signs: Don’t forget that $-3 + 5$ is NOT the same as $3 + 5$. Always keep an eye on the signs!

2. Mixing up multiplication and addition: When you see $-4 \times -2$, remember it equals a positive $8$, not $-8$. Keep that in your mind!

3. Getting division wrong: If you do $-15 \div 3$, the answer is $-5$, NOT $5$. Make sure to check your answers!

If you avoid these common mistakes, you'll be great at working with whole numbers in no time! Happy calculating!