The composite numbers are: 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86 ,87, 88
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The odd numbers between 70 and 90 are 71, 73, 75, 77, 79, 81, 83, 85, 87, and 89. We know right away that 75 and 85 are composite, since they're divisible by 5. 81 is composite since it is the square of 9. 77 is obviously divisible by 11, so it, too, is composite. 87 is divisible by 3 since 8 + 7 = 15, which is divisible by 3. Therefore, and trust me, I double-checked the rest, 75, 77, 81, 85, and 87 are the composite, odd numbers between 70 and 90.
81, 82, 84, 85, 86, 87, 88. 80 and 90 are composite too
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Composite numbers have factors other than 1 and itself. So, two good examples are: 62 and 84
The numbers in the 90s are all composite, apart from 97, which is prime.