Question 222 of 480
Find P, if 4516 - P7 = 3056
- A. 627
- B. 1167
- C. 6117
- D. 1427
Correct Answer:
B
Explanation
To solve the equation \( 451_6 - P_7 = 305_6 \), we need to convert all numbers from their respective bases (base 6 and base 7) into base 10 (decimal) so that we can perform the arithmetic operations easily.
### Step 1: Convert \( 451_6 \) to Decimal
To convert a number from base 6 to decimal, we use the formula:
\[
\text{Decimal} = d_n \cdot b^n + d_{n-1} \cdot b^{n-1} + \ldots + d_1 \cdot b^1 + d_0 \cdot b^0
\]
where \( d \) are the digits of the number and \( b \) is the base.
For \( 451_6 \):
- The digit \( 4 \) is in the \( 6^2 \) place.
- The digit \( 5 \) is in the \( 6^1 \) place.
- The digit \( 1 \) is in the \( 6^0 \) place.
Calculating this gives:
\[
451_6 = 4 \cdot 6^2 + 5 \cdot 6^1 + 1 \cdot 6^0
\]
\[
= 4 \cdot 36 + 5 \cdot 6 + 1 \cdot 1
\]
\[
= 144 + 30 + 1 = 175
\]
So, \( 451_6 = 175_{10} \).
### Step 2: Convert \( 305_6 \) to Decimal
Now, we convert \( 305_6 \) to decimal using the same method:
For \( 305_6 \):
- The digit \( 3 \) is in the \( 6^2 \) place.
- The digit \( 0 \) is in the \( 6^1 \) place.
- The digit \( 5 \) is in the \( 6^0 \) place.
Calculating this gives:
\[
305_6 = 3 \cdot 6^2 + 0 \cdot 6^1 + 5 \cdot 6^0
\]
\[
= 3 \cdot 36 + 0 \cdot 6 + 5 \cdot 1
\]
\[
= 108 + 0 + 5 = 113
\]
So, \( 305_6 = 113_{10} \).
### Step 3: Set Up the Equation
Now we can rewrite the original equation in decimal:
\[
175 - P_7 = 113
\]
### Step 4: Solve for \( P_7 \)
Rearranging the equation to solve for \( P_7 \):
\[
P_7 = 175 - 113
\]
\[
P_7 = 62
\]
### Step 5: Convert \( 62_{10} \) to Base 7
Now we need to convert \( 62 \) from decimal to base 7. We do this by dividing the number by 7 and keeping track of the remainders.
1. \( 62 \div 7 = 8 \) remainder \( 6 \)
2. \( 8 \div 7 = 1 \) remainder \( 1 \)
3. \( 1 \div 7 = 0 \) remainder \( 1 \)
Reading the remainders from bottom to top, we find that \( 62_{10} = 116_7 \).
### Step 6: Find the Final Answer
Since \( P_7 = 62_{10} \) corresponds to \( 116_7 \), we need to express \( P \) in decimal. The options provided are in decimal, so we need to convert \( 116_7 \) back to decimal to find the correct option.
Calculating \( 116_7 \):
- The digit \( 1 \) is in the \( 7^2 \) place.
- The digit \( 1 \) is in the \( 7^1 \) place.
- The digit \( 6 \) is in the \( 7^0 \) place.
Calculating this gives:
\[
116_7 = 1 \cdot 7^2 + 1 \cdot 7^1 + 6 \cdot 7^0
\]
\[
= 1 \cdot 49 + 1 \cdot 7 + 6 \cdot 1
\]
\[
= 49 + 7 + 6 = 62
\]
### Conclusion
The value of \( P \) in decimal is \( 62 \). However, the options provided do not include \( 62 \). Let's check the options again:
- A. 627
- B. 1167
- C. 6117
- D. 1427
None of these options match \( 62 \). It seems there was a misunderstanding in the options provided.
### Summary
- Convert numbers from their respective bases to decimal for easier calculations.
- Perform arithmetic operations in decimal.
- Convert the result back to the required base if necessary.
- Always double-check the options provided to ensure they match the calculated results.
**Revision Summary:**
- Convert base numbers to decimal for calculations.
- Rearrange equations to isolate variables.
- Convert results back to the required base if needed.
- Verify options against calculated results.