It is 3.
Look at the digit after the decimal point. It is 8, the number will be rounded up, to give 348 as the answer.
300
348
348.00
300
348.0
Take your choice out of: 345, 346, 347, 348 and 349
300.
350
0
Any number between 250 and 350 - including 250, but not including 350 (depending on the exact rules used, actually).
300