[ghubbard]

There is a popular [citation needed] children's song called Inchworm[0] that has a chorus that lists powers of two.

    Two and two are four
    Four and four are eight
    Eight and eight are sixteen
    Sixteen and sixteen are thirty-two 

Everyone familiar with this song would know that 16 and 16 are 32.

[0] https://en.wikipedia.org/wiki/Inchworm_%28song%29

[qb45]

Complete lyrics (is DMCA coming at me?):

  Inchworm, inchworm, measuring the marigolds
  You and your arithmetic, you'll probably go far.
  Inchworm, inchworm, measuring the marigolds
  Seems to me you'd stop and see how beautiful they are.
  
  (Kids Singing: 2 & 2 are 4, 4 & 4 are 8, 8 & 8 are 16, 16 & 16 are 32)

Nothing to do with imperial units at all.

Even if she didn't know the song, she might have learned 16+16 from those.

[TuringTest]

There's a similar song in Spanish, although it takes some detours. The maths in the song (which rhyme in Spanish) are the following:

2+2=4

4+2=6

6+2=8

...+8=16

...+8=24

...+8=32

Whole lyrics: http://www.teocio.es/portal/entretenimiento/canciones-danzas...