Nope. To work out if a number is a multiple of three - add all the digits in the number together. If the answer will divide by 3, then so will the original number. In this case, 5+8+0 = 13 - which doesn't divide by 3.
580
The first 10 multiples are 58, 116, 174, 232, 290, 348, 406, 464, 522, and 580
116, 232, 348, 464, 580, 696, 812, 928, . . .
580
The multiples of 58 are the infinite set that starts 58, 116, 174, 232, 290, 348, 406, 464, 522, 580, and so on.
No - the nearest big number divisible by 3 is 600 - which is 20 more than 580 As 20 is not divisible by 3 then also 580 is not.
193.3333
There are an infinite amount of answers to that. 290, 580, 870, 1160 and 1450 are the first 5 of them.
145, 290, 435, 580, 725, 870, 1015, 1160, 1305, 1450, 1595, . . .
The first 15 multiples of 116: 116, 232, 348, 464, 580, 696, 812, 928, 1044, 1160, 1276, 1392, 1508, 1624, 1740 . . . ∞
The first 15 multiples of 145: 145, 290, 435, 580, 725, 870, 1015, 1160, 1305, 1450, 1595, 1740, 1885, 2030, 2175 . . .
The first 15 multiples of 116: 116, 232, 348, 464, 580, 696, 812, 928, 1044, 1160, 1276, 1392, 1508, 1624, 1740 . . . ∞