Multiple choice

Directions: In the following number series, one number is wrong. Find out the wrong number. 7, 17, 45, 145, 601, 3019, 18129

  1. 601

  2. 17

  3. 145

  4. 3019

  5. 18129
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The pattern is: 7*2+3=17, 17*3-6=45, 45*4+9=201 (not 145). The sequence follows x*n + (n-1)*3 or similar. Checking 145: 45*3+10=145 is wrong. The sequence is 7, 17, 45, 145, 601... 7*1+10=17, 17*2+11=45, 45*3+10=145, 145*4+41=601. The pattern is inconsistent at 145.

AI explanation

The pattern involves multiplying the previous term by an increasing integer and then adding that same integer. The sequence of operations is multiply by 1 and add 1, multiply by 2 and add 2, multiply by 3 and add 3, and so on. Following this rule, 45 multiplied by 3 plus 3 gives 138. Because the provided series lists 145 instead of 138, the wrong number is 145.

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