Four numbers 2, -3, 5 and -7 are arranged in a pattern as shown. 2, -3, 5, -7, 2, -3, 5, -7, 2, -3 ..........

what is the 2005 number?

2 answers

2005 /4 = 501 1/4
2004/4 = 501 so -7

so
2
Please, Damon, I need the rule write in Formulas.