Find $2.5-0.32.$
I want to subtract one decimal number from another, so I need to align the decimal points and subtract each column from right to left. I can write the problem as $2.50-0.32$ to make the columns clearer. In the rightmost column, I have $0-2$, which is negative. I can't have a negative digit in the result, so I need to borrow one from the next column. That means I reduce the 5 in the next column to 4, and add 10 to the 0 in the rightmost column. Now I have $10-2=8$ in the rightmost column. In the next column, I have $4-3=1$. In the leftmost column, I have $2-0=2$. So the final answer is $2.18$.

