Both UNICEF (the authority cited in the claim) and World Bank give
42.5/1000 as the worldwide average under-5 mortality rate for 2015.
I followed round-to-even to choose 42 as the outcome.
C. J. Cherryh, "Invader", on why we visit very old buildings:
"A sense of age, of profound truths. Respect for something
hands made, that's stood through storms and wars and time.
It persuades us that things we do may last and matter."