Bob has planted corn in his garden, and it has just started to sprout. A week after planting it, it had grown 2 inches. The next week, its height increased by twice as much as it had the first week. In the third week, it grew 4 times as much as it did the week before. How tall are the corn plants now?
Let's think step by step below.
22
The second week it grew twice as much as the first week, so 2 * 2 inches = 4 inches.

The third week it grew 4 times as much as in the second week, so 4 * 4 inches = 16 inches.

In total, it grew 2 inches + 4 inches + 16 inches = 22 inches.

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The answer is 22