The question is not that dumb as it sounds because the answer is 8. And what I really want to know if there are different 5050 LED's or I've got some particulary bad batch or am I making a measurement misstake.
I've bought gauss 14.4 LED strip which is marked "5050-60P-12V-10D-V1.1" So 60 5050 LED's per meter. This should consume 14.4W boths according to descriptions of such strips and according to calculations on 5050 datasheet. But my power supply shows 2.0A at 12V for 2.95 meter strip. That's 8W per meter. Voltage on the other end of the strip is 11.6V.
The reason seems to be that voltage drop on a single LED is 2.9V when it should be 2.3V. Voltage drop on a single LED is 2.9V. For each 3 LED's there are two 39 ohm resistors (marked 390, and measurements confirm that). And I've checked my power supply (HY 3005) with resistor load, reading seems correct: 0.17A at 4V for 23.5 ohm (two 47 in parallel).
I've made a mistake by not describing the strip properly and not giving datasheets. This is a warm white strip and it's target voltage is really 12 volts. It's for home usage and is meant to be used with 12V power supply which you can buy in the same store. That supplies can't give 14.4 volts.
Unfortunately manufacturers site is very uninformative so there is no point to linking to it. There is also no datasheet available and I don't know LED's manufacturer. So I can only use datasheets for similar LED's. 3V drop for white LED seems OK, 2.3V from unedited question was for red LED's, which is a mistake.
All components in the strip seems to be fine, it's just designed to drain less power than specified at 12V. Probably that's made for extending lifetime. Or, as @TonyStewart.EEsince'75 noted, extra room is left to allow usage of the same strips in cars at 14.4V. By increasing voltage I can make it brighter and still will be within allowed current limits for LED's, but stock power supplies for that strips can be maximally adjusted to 13V.