Russian-English translations for добавка

• additive
  Matrix multiplication is additive, in that M\vec v+M\vec w=M(\vec v+\vec w
  It is natural to look at a finite cyclic group as an additive group
  Oil may be used as an additive in gasoline to improve the lubrication of a small engine
• refill
  Today it is $2 for a coffee, with free refills throughout the day.
  Were cutting back. No new printers or pens, just refills.
  Can you refill my cup please? Ive finished my coffee.
• second
  He lives on Second Street
  The second volume in "The Lord of the Rings" series is called "The Two Towers
  You take the first one, and Ill have the second