The + sign in front of a number for example, +350 means that a bet has been placed on the underdog, and the three digits following that sign indicate the amount paid out if the bet wins and the bettor had wagered $100.
What Does a +1.5 Spread Mean? A +1.5 spread is commonly seen in baseball betting, the standard runline for MLB. This spread means the underdog must win outright or lose by exactly one run to cover the spread. Alternatively, a -1.5 spread means that the favorite must win by at least two runs.