We want to figure out which number, when multiplied by the single digit in its tens position, will result in:
1) A 3 digit number
2) A number with the same units and tens digit
I notice that B and D have tens digit 5. I think they are good possibilities to fit the bill, since 5*odd number always ends in 5 (and we know all of the digits are odd.) This makes it highly likely that the last two digits will be the same.
First I try B, 353. I want to work out 353*5. I remember that 333.333*3 = 1000. Since both parts of the product 353*5 are bigger than that, we know this results in something over 1000. This does not fit the bill since it is not a 3 digit number.
Now I try D, 151. I line up the multiplication problem:
151
X 5
I see I get a 5 in the units digit, then a 5 in the tens digit... I don't need to worry about carrying the 2 or going any further because I know this is a 3 digit number whose last two digits are the same.
So, the answer is D.
Tatiana Becker | GMAT Instructor | Veritas Prep
