Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

1. What is the 5th prime number, which is also an additive prime?

2. What is a Mersenne prime?

Note: Use hide tags.

Scoreboard

No one yet!

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

Easy, right? No scoreboard this time.

3. Complete the sequence: 3, 7, 13, 19, 29, __ , __

4. What is the perfect number that when you subtract 1 to it, you get a prime?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

Yes.

5. What is the prime exponent of 5 wherein when added the digits of the number, you get a prime number (5^n = digit 1 + digit 2... = p)?

6. Which is the first twin triplet (3 consecutive twin primes)?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

That was a tricky one!

7. Complete the digits:

8. Is 36+(9*12)-(11*(2+3) prime?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

I do not understand 7.

8 is missing a parentheses.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

Hint: On 7, it is the largest known prime.

For 8, whoops, sorry.

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

7. Yes.

8. The answer was 89. Good.

9. When counted the letters of mathaholic, is it prime or composite?

10. What is the first prime number from 201 - 300?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

For 9) the number of letters you want counted?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

Number of letters of my username, mathaholic.

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

]

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

11. Is this true? c + c = p

12. What is the 1,000,000th prime number?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

11) I do not understand the question.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

11. Composite number + Composite number = prime number

12. Good. Just 11

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

Sometimes it is false, too: 4 + 6 = 10, or 4 + 4 = 8

13. You might not be able to answer this: What is 13^13 - (13*(13th prime number)) ?

14. Let's ease it off a little. If 2 + 3 = 5, what is 3 + 5 ? **Note: This is not literal addition.**

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

13. Okay.

14. I actually made a puzzle of 1 + 4 = 9 = 4 + 9 = ?.

Now, look:

2 is the first prime number, and 3 is the second prime number. Add the orders, 1 + 2 = 3rd prime number = 5.

3 is the second prime number, and 5 is the third prime number. 2 + 3 = 5th prime number = 2, 3, 5, 7, **11**.

15. What is the 17th prime number?

16. Square the 17th prime number, and what is it?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

There are 2 answers for 16:

17[sup]2[/sup] = 289

The 289th prime number is 1,879

Another solution is what you did: 17p[sup]2[/sup]

17. What is the 5th prime number + the 5th prime number squared?

18. What is the 8th prime number + the 1st prime number cubed?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 104,193

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**

Offline

**mathaholic****Member**- From: Earth
- Registered: 2012-11-29
- Posts: 3,246

17. Good

18. Good

Bonus!

19 - 20. If 97 is the 25th prime number, is 199 the 50th prime number? If no, what is it?

Mathaholic | 10th most active poster | Maker of the 350,000th post | Person | rrr's classmate

Offline