The greatest common factor (GCF) of 16 and 12 is 4. This is the largest number that evenly divides 12 and 16. It can be found by looking at the factors of those numbers:
12 = 4·3
16 = 4·4
Or it can be found by seeing if the difference of the numbers (4) evenly divides them both. It does, so that is the GCF.
The greatest number of sets Mandy can make is 4.
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Each of Mandy's 4 sets will have 4 sheets of paper and 3 envelopes.
