Bunuel wrote:

How many two-digit numbers are divisible by both 5 and 6?

(A) none

(B) one

(C) two

(D) three

(E) more than three

Two-digit numbers: 10 to 99

Divisible by 5 and 6 means:

For 5, must end in 5 or 0

For 6: must be divisible by 2 and 3

Use those prime factors: 5, 2, and 3

LCM = (5 * 2 * 3) = 30

30 is one multiple. Multiply by increasing integers

(30 * 1 = 30)

30 * 2 = 60

30 * 3 = 90

Next multiple of 30 is 120. Too large

There are three two-digit numbers divisible by 5 and 6: 30, 60, and 90

Answer

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that within me there lay an invincible summer.

-- Albert Camus, "Return to Tipasa"