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What is the missing number in the series: 12, 25, 51, 103, ?
207
205
209
211
207
Multiply each term by 2 and add 1 to find the next number in the sequence.
Multiply each term by 2 and add 1 to find the next number in the sequence.
Analyze the first transition
Multiply the first term 12 by 2 and add 1 (12 multiplied by 2 plus 1 equals 25) to arrive at the second term.
Verify the pattern across terms
Apply the same rule to the subsequent terms: 25 multiplied by 2 plus 1 equals 51, and 51 multiplied by 2 plus 1 equals 103.
Calculate the missing number
Multiply the last given term 103 by 2 and add 1 (103 multiplied by 2 plus 1 equals 207) to find the missing number.
B: 205 is incorrect because 103 multiplied by 2 plus 1 is 207 not 205. C: 209 is incorrect because it results from an incorrect arithmetic calculation. D: 211 is incorrect because it overshoots the correct calculated value of 207.
A is correct because each consecutive number in the series is generated by multiplying the preceding number by 2 and adding 1, yielding 103 multiplied by 2 plus 1 equals 207.
When numbers double or grow rapidly, test combination patterns involving multiplication followed by a constant addition or subtraction.
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