Subject :IMO Class : Class 6
Observe the following patterns. Then find the sum of 1 + 3 + 5 + 7 + 9 + ... + 19.
1 ------------------------= 1 × 1 = 1
1 + 3 -------------------= 2 × 2 = 4
1 + 3 + 5 --------------= 3 × 3 = 9
1 + 3 + 5 + 7 ---------= 4 × 4 = 16
1 + 3 + 5 + 7 + 9 -----= 5 × 5 = 25
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A 121
B 81
C 100
D 64
Ans 1:
Class : Class 4
its none of the above