Rhona wrote down a list of nine multiples of ten: 10, 20, 30, 40, 50, 60, 70, 80, 90. She then deleted some of the nine multiples so that the product of the remaining multiples was a square number.
What is the least number of multiples that she could have deleted?
Select one option, then click Submit.
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Select an option, then submit.
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Pink Kangaroo 2019 (2019)
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