Question
Find the sum of the first 30 natural
numbers.Solution
Sum of first 'n' natural numbers = n(n + 1) ÷ 2
Required sum = 30 × (30 + 1) ÷ 2 = 30 × 31 ÷ 2 = 465
169, 224, 293, 385, 497, 629
Find the wrong number in the given number series.
20, 33, 50, 69, 93, 121
25Â Â Â 26Â Â Â Â 28Â Â Â Â 32Â Â Â Â 42Â Â Â Â 56
Find the wrong number in the given number series.
8, 12, 23, 40, 66, 103
8137, 5405, 3669, 2701, 2201, 1997
Find the wrong number in the given number series.
78, 66, 51, 39, 20, 12
2824Â Â Â Â 2314Â Â Â Â Â 1973Â Â Â Â 1759Â Â Â Â 1634Â Â Â Â 1574
In each of the following number series, one term is wrong. Find the wrong term.
3, 7, 13, 21, 31, 42, 57
Find the wrong term in the given series below.
2847, 2954, 2799, 3088, 2727, 3256
Find the wrong number in the given number series.
2, 5, 10, 17, 26, 38, 50