big friend

English

Noun

big friend (plural big friends)

1. (education, abacus jargon) A natural number which when added to another number equals 10.

   The big friend of 3 is 7 because 3 + 7 = 10.

   • 2023 May 17, u/silly_rabbit289, “Shakuntala Devi The Indian who was known as a human computer for her mental math skills.”, in Reddit‎^[1], r/nextfuckinglevel, archived from the original on 2023-05-17:

     I tried learning abacus but left it cause it was too boring for me. All I learnt was 7 is the big friend of 3 lol.

2. Used other than figuratively or idiomatically: see big,‎ friend.

Coordinate terms

• little friend