Praxis 5003 Practice Question
Which of the following is a way to quickly multiply 24 by 16 without a calculator?
Correct Answer: A
Rationale: Option A effectively uses the difference of squares method. By calculating \(20 \times 20\) (which equals 400) and subtracting \(4 \times 4\) (which equals 16), you arrive at \(400 - 16 = 384\), the product of 24 and 16.
Option B only provides \(20 \times 20 = 400\), which does not yield the correct product.
Option C calculates \(20 \times 10 = 200\) and adds \(4 \times 6 = 24\), resulting in \(200 + 24 = 224\), which is incorrect.
Option D computes \(25 \times 10 = 250\) and adds \(4 \times 15 = 60\), giving \(250 + 60 = 310\), also incorrect.
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