Basic Arithmetic Practice: Two-Digit Minus Single-Digit Subtraction

To solve this problem, we will perform vertical subtraction with regrouping:

Step 1: Set up the subtraction vertically:

$\begin{aligned} 88& \\ -~~~ 9& \\ \hline & \phantom{\ } \\ \end{aligned}$

Step 2: Compare the unit places:

The units digit in 88 (8) is less than the units digit in 9 (9), necessitating regrouping.

Step 3: Regrouping:

• Borrow 1 ten from the tens digit (8 tens becomes 7 tens).

• Add that ten to the units digit, making it $18$ instead of $8$.

Step 4: Perform the subtraction:

• Subtract the units place: $18 - 9 = 9$.

• Subtract the tens place: $7 - 0 = 7$, since the tens place in 9 is effectively 0.

Step 5: Combine the results.

The difference is $79$.

Thus, the solution to the subtraction problem is $79$.