Explanation

The GRE calculator only displays eight digits, so you would get an “Error” message if you tried to solve this multiplication problem with the GRE calculator during the test. While you can certainly multiply 725,278 by 67,066 by hand, you would waste valuable time (not to mention open yourself up to careless mistakes) because you really only need to multiply the last two digits of each number:

\(725278 \times 67066\)	\(78 \times 66\)
\(48641494348\)	\(5148\)

And \(x = 4\), \(y = 8\)

Now find the sum of x + y: 4 + 8 = 12. Hence option A is correct.
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multiply the last 2 digits of both numbers instead of wasting time solving the entire multiplication, the product will give a 4 digit number which will give the units and 10s digit as required

78 X 66 = 78 X 2 X 3 X 11 = 156 X 3 X 11 = 468 X 11 = (460+8) X 11 = 5060 + 88 = 5148

so, 8 + 4 = 12

725,278
67,066
------------
68
8x
--------------
......48
4+8=12
Ans. A

I did this same method on the test and got it right, but it was more of an educated guess. Is this strategy true for all products? And does it also work for the hundreds digit, thousands, etc.? Thanks!

Yes.

it will work with all numbers.
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