Adding Hexadecimal Numbers:
To add hexadecimal numbers, you apply the same “grade-school” idea as decimal addition, but with base instead of base : add digits right-to-left, track carries, and treat digits – and – as values –. keyword
For our problem we compute . We will show: (1) digit-by-digit base- addition with carries, (2) a validation via conversion to decimal and back, and (3) generalizable patterns for future problems.
Key terms: hexadecimal numeral digit value carry base-16
Hexadecimal Addition (Carry) Tutorial
Let’s align the numbers by place value (units on the right).
has 4 hex digits; has 4 hex digits, so we can line up directly:
| Place (base ) | ||
|---|---|---|
We’ll add digit-by-digit from the rightmost column, using carry whenever a column sum reaches or more.
Digit-by-Digit Hex Addition with Carries
- 1Step 1
Add (in hex digit values). Since , , which is less than , so the result digit is and carry is .
- 2Step 2
Add . Here , , carry : . In base , , so remainder is and carry is .
- 3Step 3
Add . Here , , carry : . In base , , so remainder is and carry is .
- 4Step 4
Add . Here , , carry : . Since , remainder digit is and carry becomes .
- 5Step 5
Combine the column remainders from left to right: . Therefore, .
Fast carry rule in base $16$
When a column sum is , write it as . The remainder directly becomes the hex digit (0–F).
Common mistake: forgetting that A–F represent 10–15
Always convert hex digits to their numeric values before adding: , , , , , . Otherwise carries will be wrong.
We now verify the result by converting to decimal and back.
1) Convert to decimal
Using place values:
So:
2) Convert to decimal
So:
3) Add in decimal, then convert back
Sum:
Now check :
So:
The decimals match, confirming:
Column Sums and Remainders (Base 16)
Each hex column is summed (including carry), then split into carry + remainder.
How to Solve Any Hex Addition Problem
Align digits
1Place numbers so the rightmost digits line up by place."
Add right-to-left
2Compute each column sum using digit values (– = 10–15)."
Compute carry and remainder
3For sum , carry is and remainder is ."
Convert remainder back to hex digit
4Map remainder 0–15 to hex digit 0–F, then write the final result."
Common Edge Cases
Knowledge Check
What is the value of hex digit in base 10?