Scala: How do I make those codes more simple? -

how make following codes more simple? quite new scala. in advance!

example 1:

def xsum(n: int): int = {    if (n<10) n else n%10+xsum(n/10) }

example 2:

def num(n: int): int = {   if (xsum(n)%10==0) n else (100-xsum(n))%10 + n*10 }  def xsum(n: int): int = {     if (n<10) n else n%10 + xsum(n/10) }

example 3:

def tru(n: int): boolean = {   n==0 || xsum(n)%10==0 } def xsum(n: int): int = {   if (n<10) n else n%10 + xsum(n/10) }

def xsum(n:int):int= n.tostring.map(_-'0').sum

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