AMC 10B 2025 (Problem 18)

Sequences & SeriesMedium

What is the ones digit of the sum

\lfloor\sqrt1\rfloor+\lfloor\sqrt2\rfloor+\lfloor\sqrt3\rfloor+\cdots+\lfloor\sqrt{2025}\rfloor?

(Recall that

\lfloor x\rfloor

represents the greatest integer less than or equal to

x

\text{(A)}\;1

\text{(B)}\;2

\text{(C)}\;3

\text{(D)}\;5

\text{(E)}\;8