Calvin is a bug collector.  In his collection, he has 12 giant roaches, 3 scorpions, half as many crickets as roaches, and twice as many caterpillars as scorpions.  How many insects does Calvin have in his collection?
With half as many crickets as roaches, he has 12/2=<<12/2=6>>6 crickets.
With twice as many caterpillars as scorpions, he has 3*2=<<3*2=6>>6 caterpillars.
In total, he has 12+3+6+6=<<12+3+6+6=27>>27 insects in his bug collection.
#### 27