1. express 21 as the sum of two prime numbers

Solution:
We can write `21` as

`2+19=21`

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2. express 44 as the sum of two prime numbers

Solution:
We can write `44` as

`3+41=44`

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3. express 24 as the sum of two prime numbers

Solution:
We can write `24` as

`5+19=24`

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4. express 21 as the sum of three prime numbers

Solution:
We can write `21` as

`2+2+17=21`

`3+5+13=21`

`3+7+11=21`

`5+5+11=21`

`7+7+7=21`

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5. express 21 as the sum of three odd prime numbers

Solution:
We can write `21` as

`3+5+13=21`

`3+7+11=21`

`5+5+11=21`

`7+7+7=21`

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6. express 49 as the sum of three odd prime numbers

Solution:
We can write `49` as

`3+3+43=49`

`3+5+41=49`

`3+17+29=49`

`3+23+23=49`

`5+7+37=49`

`5+13+31=49`

`7+11+31=49`

`7+13+29=49`

`7+19+23=49`

`11+19+19=49`

`13+13+23=49`

`13+17+19=49`

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7. express 31 as the sum of three odd prime numbers

Solution:
We can write `31` as

`3+5+23=31`

`3+11+17=31`

`5+7+19=31`

`5+13+13=31`

`7+7+17=31`

`7+11+13=31`

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