Library›Addition Fluency›One card

A LITTLE SOMETHING WORTH KNOWING

A small discovery. Yours to pass on.

Math & LogicOne small ahaSum

13 + 27

Think it. Then flip it. ahamoraTap to reveal Back to the cue
Math & LogicOne small aha
Your new aha40

13 + 27 = 40. Changing the order gives 27 + 13, the same sum. Source: Addition ↗

ahamoraReference ↗

Keep the thread going

One answer is a beginning.

Share a little curiosity, or follow it into the full collection.

Flip the full deck →

More from Addition Fluency

A few more worth knowing.

  1. 38313 + 28RECALL
    41

    Mental addition

    Open this card ↗
  2. 38413 + 29RECALL
    42

    Mental addition

    Open this card ↗
  3. 38513 + 30RECALL
    43

    Mental addition

    Open this card ↗