Let's solve $1 - 90$ step by step! Imagine you have 🍎 just 1 apple. **Box 1:** Now you want to take away 90 apples, but you only have 1 apple. This means you go into negative numbers because you owe 89 apples! So, $1 - 90 = -89$. Great job! You learned about negative numbers! 🎉