WordReference English-Spanish Dictionary © 2014:

Principal Translations
sumar vtrverbo transitivo: Verbo que requiere de un objeto directo ("di la verdad", "encontré una moneda"). (operación aritmética)equal vtrtransitive verb: Verb taking a direct object--for example, "Say something." "She found the cat."
  make vtrtransitive verb: Verb taking a direct object--for example, "Say something." "She found the cat."
  be equal to v exprverbal expression: Phrase with special meaning functioning as verb--for example, "put their heads together," "come to an end."
  add up to, come to v exprverbal expression: Phrase with special meaning functioning as verb--for example, "put their heads together," "come to an end."
 3 más 5 suman 8.
 Three plus five equals eight.
 Three and five make eight.
sumar vtrverbo transitivo: Verbo que requiere de un objeto directo ("di la verdad", "encontré una moneda"). (añadir, agregar)add vtrtransitive verb: Verb taking a direct object--for example, "Say something." "She found the cat."
 La dirección corporativa sumó a un experto en mercadotecnia a su equipo.
 The company directors added a marketing expert to their team.
 
Additional Translations
sumarse v prnlverbo pronominal: Verbo que se conjuga con un pronombre átono ("me", "te", "se") que concuerda con el sujeto ("lavarse", "irse", "enojarse"). (adherirse, incorporarse)join vtrtransitive verb: Verb taking a direct object--for example, "Say something." "She found the cat."
 Mi hermano desea sumarse al proyecto.
 My brother wants to join the project.
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WordReference English-Spanish Dictionary © 2014:

Compound Forms:
sumar esfuerzos join efforts
sumar tiempo count time
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'sumar' found in these entries
In the Spanish description:
English:

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