There’s a big discrepancy between the number of Williams math majors reported by IPED and the number listed on Williams website. My guess is that the reason for the discrepancy is that Williams counts double majors twice and IPED only counts one major per student. Since about 40% of Williams students double major, the difference is significant.
IPED 23
Williams website 64
https://communications.williams.edu/media-relations/fast-facts/