What is the next number in the series: 1, 2, 4, 7, 11, 16 ...?

To determine the next number in the series 1, 2, 4, 7, 11, 16, let's first analyze the pattern by examining the differences between each pair of consecutive numbers.

• The difference between 1 and 2 is 1.

• The difference between 2 and 4 is 2.

• The difference between 4 and 7 is 3.

• The difference between 7 and 11 is 4.

• The difference between 11 and 16 is 5.

Observing these differences, we see that they form an increasing sequence: 1, 2, 3, 4, 5. This indicates that the next difference should be 6.

Adding this difference to the last number in the series:

16 + 6 = 22.

Thus, the next number in the sequence is 22. This understanding confirms that the correct answer is indeed C.