## Friday, October 30, 2009

### Continue the Sequence of Numbers

8960, 6720, 3360, 840, 630, ...

1. 315

The differences between the numbers are: 2240, 3360, 2520, and 210. That doesn't follow any discernable pattern, unless you look at the ratio of the differences to the original number:

2240 / 8960 = .25
3360 / 6720 = .5
2520 / 3360 = .75
210 / 840 = .25

So, we have a repeating sequence in the ratios { .25, .5, .75 }. The next in the sequence is .5, , meaning the next number will be half the current number, hence 315.

2. 8960 * 0.75 = 6720
6720 * 0.5 = 3360
3360 * 0.25 = 840
again...
840 * 0.75 = 630
630 * 0.5 = 315
315 * 0.25 = 78.75 ......

so the seq would be
8960, 3360, 840, 630, 315, 78.75, ......

3. As always, you impress me with how you get these. The answer, as already pointed out by harryc and sadeesh is 315.

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