Do we round up or down the damage from spells?

@JeremyECrawford Do we round up or down the damage from spells? What about concentration saves? Is there a general rule? Thanks

— dimitris andjus (@dimitrisandjus) October 28, 2016

When you divide a number, you round down, unless a rule tells you otherwise (see PH, 7). #DnD https://t.co/MoTylZI9rm

— Jeremy Crawford (@JeremyECrawford) October 28, 2016