1. ## 20th Number

In the sequences below, can you determine the 20th number?

A.) 2, 9, 28, 65, 126, ...

B.) 139, 191, 251, 319, 395, ...

2. ## Re: 20th Number

A) <span style="background-color: #FFFF00; color: #FFFF00; font-weight: bold">8001</span hide>

3. ## Re: 20th Number

[img]/forums/images/smilies/cool.gif[/img] <span style="background-color: #FFFF00; color: #FFFF00; font-weight: bold">2495</span hide>

4. ## Re: 20th Number

You got A correct but B is <span style="background-color: #FFFF00; color: #FFFF00; font-weight: bold">also correct</span hide>. <img src=/S/bananas.gif border=0 alt=bananas width=33 height=35>

5. ## Re: 20th Number

B <span style="background-color: #FFFF00; color: #FFFF00; font-weight: bold"> I thought I would give an explanation:

The difference between the first term and the second term is 52, I add 8 to make 60)and this is the difference between the second and the third. Each increment is the addition of 8.

The series will go:

139 191 251 319 395 479 571 671 779 895 1019 1151 1291 1439 1595 1759 1931 2111 2299 2495

</span hide>

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