The missing number is 399.

Explanation:

84 = 4^3 + 4^2 + 4^1

155 = 5^3 + 5^2 + 5^1

258 = 6^3 + 6^2 + 6^1

584 = 8^3 + 8^2 + 8^1

819 = 9^3 + 9^2 + 9^1

Thus,

399 = 7^3 + 7^2 + 7^1

+2 votes

Can you find a pattern and find the missing number in the series given below - 84, 155, 258, ? , 584, 819.

+2 votes

+2 votes

Pattern: 84, 155, 258, 399, 584, 819

Missing number: 399

Logic:

Difference of Difference between two numbers is incremented by 6

Difference between 2 numbers :

155-84 = 71

258-155 =103

399-258 =141

584-399 = 185

819-584 = 235

And the difference of difference :

103-71 = 32

141-103 = 38

185-141 = 44

235-185 = 50

Difference incremented by 6

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