Find Out the Missing Number in the Series 15, 21, 57, ?, 221.
Find out the missing number in the series 15, 21, 57, ?, 221.
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its 121.
1+4=5
5+16=21
21+36=57
57+64=121
121+100=221
looking at the pattern, you can see that you add even squares (so 2^2 4^2 6^2 8^2 and 10^2)
1+4=5
5+16=21
21+36=57
57+64=121
121+100=221
looking at the pattern, you can see that you add even squares (so 2^2 4^2 6^2 8^2 and 10^2)
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