Q:

# Which number best completes the sequence: 2, 9, 5, 13, 10, 19 and 17?

A:

The number 17 best continues the following sequence: 2, 9, 5, 13, 10, 19. A sequence, in math terms, is a set of numbers organized in some sort of pattern. To find the next number in the sequence, the problem's solver must first figure out the pattern.

## Keep Learning

The differences between the numbers are 7, -4, 8, -3 and 9. The numbers switch on and off from adding or subtracting. Every time a number is added, it is one higher than the last number that was added. In the pattern so far, the positive numbers are 7, 8, and 9. Every time a number is subtracted, it is one less than the last subtraction. The negative numbers so far are -4, and -3. Using this pattern, the next number is 2 less than the last number in the sequence, 19. So, the answer is 17.

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## Related Questions

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According to Common Core standards, the first concepts a student should learn in math are the names of the numbers and the sequence in which to count them. From there, students are able to begin learning simple addition and subtraction.

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A numeric order is a way to arrange a sequence of numbers and can be either ascending or descending. For example, an ascending numerical order of area codes for the United States starts with 201, 203, 204 and 205.

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Some ideas for a mathematics project are creating curves with straight lines, understanding the fourth dimension, pi generation, and applications for the Fibonacci sequence. These projects are useful and interesting for various education levels from elementary school to college.