ACT Exam Prep (Math and English)

Category - Mathematics

Kathleen projects her expenditures for purchasing office supplies to be $85/week. How much will she spend on office supplies over a 4-week time span?
  1. $290
  2. $325
  3. $340
  4. $355
  5. $342
Explanation
Answer: $340. It is very easy to mentally multiply a number by 4. Simply double the number, then double that resulting number. In this case, 85 doubled is 170, and 170 doubled is 340.

Key Takeaway: This trick of doubling numbers twice in order to multiply by four comes in handy when you are doing calculations related to quarters, for example. This isn’t a tough question, but speed is what matters here.
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