1. **Problem:** Put the numbers $2.3 \times 10^2$, $\sqrt{400}$, $5^3$, $0.4$, and $1 \times 10^3$ in order from least to greatest. 2. **Step 1:** Calculate each number. - $2.3 \times 10^2 = 230$ - $\sqrt{400} = 20$ - $5^3 = 125$ - $0.4 = 0.4$ - $1 \times 10^3 = 1000$ 3. **Step 2:** Order the numbers from least to greatest: $$0.4 < 20 < 125 < 230 < 1000$$ 4. **Final answer:** $0.4, 20, 125, 230, 1000$