Numeracy, or, "the ability to use and understand numbers in daily life" is a critical component of health literacy. However, little research has focused on numeracy in young adults (ages 18-29). We used a national sample to examine how health-information seeking, trust in sources, and interactions with health care providers differ for young adults with lower and higher numeracy. We included respondents ages 18 to 29 (n = 661) from the latest administration (2008) of the Health Information National Trends Survey (HINTS). There were no significant differences between those with lower and higher numeracy for most sociodemographic variables, nor did numeracy predict trust in health information sources. However, there were several differences for health-information seeking and health-provider interactions. Those with lower numeracy were significantly more likely to say their most recent search took a lot of effort (46% vs. 24%, p = .0008) and was frustrating (45% vs. 22%, p = .0038). Those in the lower numeracy group also reported more negative interactions with health providers, including feeling less able to rely on their provider (62% vs. 86%, p < .0001), and less likely to say their provider made sure they understood information (70% vs. 88%, p = .0001) and helped with any uncertainty (51% vs. 75%, p < .0001), even when adjusting for other variables. Our data suggest that limited comfort with numbers and statistics can influence a variety of health-related factors for young adults. More research is needed to understand how health literacy skills--including numeracy--influence health-information seeking, patient-provider relationships, and health outcomes, for young adults.