The battery charge in Mary’s cordless vacuum cleaner lasts ten minutes. It takes her four minutes to vacuum each room in her house. Mary has three bedrooms, a kitchen, and a living room. How many times does Mary need to charge her vacuum cleaner to vacuum her whole house?
Mary has 3 + 1 + 1 = <<3+1+1=5>>5 rooms in her house.
At 4 minutes a room, it will take her 4 * 5 = <<4*5=20>>20 minutes to vacuum her whole house.
At 10 minutes a charge, she will need to charge her vacuum cleaner 20 / 10 = <<20/10=2>>2 times to vacuum her whole house.
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