Hello, the problem is as follows. Please note: I have an answer to this particular question.
If 893 X 78 = p, which of the following is equal to 893 X 79?
P+1
P+78
P+79
P+893
P+894
The answer to this question goes along the lines of
893 x 79 = 893 x 78 + 1 and etc... But is there another way to get this question?
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Which of the following is equal?
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DavidG@VeritasPrep
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You could also use units digits. If P = 893 *78, P will have a units digit of 4. (3*8 = 24.)
893 * 79 will have a units digit of 7. (3 * 9 = 27.)
So the correct answer must have a units digit of 7.
D : P + 893, and P has units digit of 4, so P + 893 will have a units digit of 7.
893 * 79 will have a units digit of 7. (3 * 9 = 27.)
So the correct answer must have a units digit of 7.
D : P + 893, and P has units digit of 4, so P + 893 will have a units digit of 7.
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Brent@GMATPrepNow
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Here's the solution you referred to:datonman wrote: If 893 x 78 = P, which of the following is equal to 893 x 79?
A) P+1
B) P+78
C) P+79
D) P+893
E) P+894
Given: 893 x 78 = P
893 x 79 = 893 x (78 + 1)
= (893)(78) + (893)(1)
= P + 893
= D
Cheers,
Brent
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Hi All,
We're told that 893 x 78 = P. We're asked which of the following is equal to 893 x 79.
Most GMAT questions are designed so that they can be approached in more than one way. Sometimes how you think about the information that you're given can provide a 'logic shortcut' that you can take advantage of (to reduce the amount of work needed to answer the question and save time).
Here, we're told that P = (78)(893). If you look at that calculation a certain way, it's the same as saying "P equals seventy-eight 893s." The question asks which of the following is equal to 'seventy-nine 893s?" Looking at the information - and the question - in those terms, the answer is pretty clear: P and another 893.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich
We're told that 893 x 78 = P. We're asked which of the following is equal to 893 x 79.
Most GMAT questions are designed so that they can be approached in more than one way. Sometimes how you think about the information that you're given can provide a 'logic shortcut' that you can take advantage of (to reduce the amount of work needed to answer the question and save time).
Here, we're told that P = (78)(893). If you look at that calculation a certain way, it's the same as saying "P equals seventy-eight 893s." The question asks which of the following is equal to 'seventy-nine 893s?" Looking at the information - and the question - in those terms, the answer is pretty clear: P and another 893.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich
[1] Find Alternate Form
$$893 \times 79 \equiv 893 \times (78 + 1) = (893 \times 78) + (893) $$
[2] Substitute
$$ \text{Since } p = 893 \times 78 \text{, substitute this into the above equation.} $$
$$ p + 893$$
Answer D
$$893 \times 79 \equiv 893 \times (78 + 1) = (893 \times 78) + (893) $$
[2] Substitute
$$ \text{Since } p = 893 \times 78 \text{, substitute this into the above equation.} $$
$$ p + 893$$
Answer D
