or $64 ques·tion
[siks-tee-fawr-dol-er kwes-chuh n, -fohr-]
the critical or basic question or problem: Whether the measure will get through Congress this session or not is the sixty-four-dollar question.
Origin of sixty-four-dollar question
from the fact that 64 dollars was the largest prize on a popular radio quiz show in the 1940s
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019