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The process would be easier if there was only one payment, but there must be some security or financial reason for Paypal to send you two random payments

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migrated from ux.stackexchange.com May 4 '12 at 13:54

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I suspect a 1 in 99 chance of guessing the deposit amount on a fake account using a stolen card, the odds were just too high.

There's 9801 (99 x 99) possible outcomes that anyone trying to guess the deposits would have to pick from - vs the 99 outcomes from one payment.

In order to achieve the same number of outcomes from one payment they would have to deposit anything between 0.01 and 98.01 which would be very generous of them.

But not a UX question really.

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I'd be happy if a vendor deposited $98.01 into my account purely for verification ;) – bangdang May 4 '12 at 15:30
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Actually only 4900 possibilities... they could be entered in either order. But still far better than 99. – Myrddin Emrys May 4 '12 at 18:34
@MyrddinEmrys: who says they need to be different? – Marjan Venema May 5 '12 at 9:06
@MarjanVenema They don't, but that doesn't change the fact that there are 4900 possibilities, not 9801. :-) – Myrddin Emrys May 5 '12 at 17:28
@MyrddinEmrys: ok help me out then. Why only half? First payment has 99 possible amounts, so does the second. That boils down to 9801 possible combinations. The only way to half that number would be a constraint that the total does not exceed a dollar? But that is mentioned anywhere, so what do I miss? – Marjan Venema May 5 '12 at 19:53
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