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MathNet 2022-part-03 — 197 problems (EN–VI) Question 184

Math Olympiad Vault · MathNet 2022-part-03 — 197 problems (EN–VI)

Question 184

Sofie and her grandmother both have their birthday on 1 January. In six consecutive years, the age of grandma is an integer multiple of the age of her granddaughter Sofie. In the seventh year this is not the case. A few years later the age of grandma is again an integer multiple of the age of Sofie.
How old can grandma be by then?
A) 63 B) 66 C) 70 D) 90 E) 91