Answer
$1,866,442,158,555,975$
Work Step by Step
RECALL:
${n}\choose{k}$$=\dfrac{n!}{k!(n-k)!}$
Use the formula above to obtain:
${55}\choose{23}$$\require{cancel}
\\=\dfrac{55!}{23!(55-23)!}
\\=\dfrac{55!}{23!32!}
\\=1,866,442,158,555,975$