Discussion
Except for the first two numbers, every number in the sequence –1, 3, 2, . . . is the sum of the two immediately preceding numbers. How many numbers of this sequence are even?
*This question is included in Nova Math - Problem Set Y: Sequences & Series, question #9
| (A) | none |
| (B) | ... |
| (C) | ... |
| (D) | ... |
| (E) | ... |
| (F) | ... |
The solution is
Posted: 09/26/2014 15:32
How many numbers are we expected to project in problems like this? We could potentially waste a lot of time looking for numbers that may not exist.
Posted: 09/26/2014 16:41
Darren, not very many. From the answer choices in this problem, we know we are looking for at least 3 even numbers, and we can see that it repeats every 4th number.
In other cases, we can usually create a formula to do the computation.
The problem needs to be solved in 1-2 minutes.
In other cases, we can usually create a formula to do the computation.
The problem needs to be solved in 1-2 minutes.
Posted: 06/27/2015 15:19
Isn't the order( -1,3,2,5,7,12,19,21,40,61,101,162...
If we add immediately preceding number.
If we add immediately preceding number.
Posted: 06/27/2015 22:30
Hi Munir,
12 + 19 = 31, not 21.
Nova Press
12 + 19 = 31, not 21.
Nova Press