Question

What is $ - 64 $ divided by 0.8?

Answer 1

Hint: We are supposed to divide a whole number by a decimal number. First of all, convert the decimal number into fraction and then multiply the two numbers by taking the reciprocal of the fraction.

Complete step-by-step answer:
In this question, we are given two numbers $ - 64 $ and 0.8 we need to divide them.
Here, the dividend is $ - 64 $ and the divisor is 0.8.
Now, for dividing them, we need to convert 0.8 into fraction.
Conversion of decimal to fraction:
Step 1:
Identify the number of digits after the decimal point. In our question, there is only one point after the decimal point.
Step 2:
If there is one number after the decimal point, multiply and divide the decimal number with 10.
If there are two numbers after the decimal point, multiply and divide the decimal number with 100.
In our question, there is only one number after the decimal point, so we have to multiply and divide the given decimal number by 10.
 $
   \Rightarrow 0.8 = 0.8 \times \dfrac{{10}}{{10}} \\
   \Rightarrow 0.8 = \dfrac{8}{{10}} \\
  $
Hence, we have converted 0.8 decimal to $ \dfrac{8}{{10}} $ fraction.
Now, we need to divide $ - 64 $ with $ \dfrac{8}{{10}} $ .
Division of whole number and a fraction:

Step 1:
Write down the numbers to be divided.
 $ - 64 \div \dfrac{8}{{10}} $
Step 2:
There is a rule that when dividing a whole number with a fraction, you can multiply the whole number with a fraction by writing the reciprocal.
 $ \Rightarrow - 64 \times \dfrac{{10}}{8} $
Now, $ 64 = 8 \times 8 $ so 8 gets cancelled from numerator and denominator.
 $
   \Rightarrow - 8 \times 10 \\
   \Rightarrow - 80 \;
  $
Hence, $ - 64 $ divided by 0.8 is $ - 80 $ .
So, the correct answer is “-80”.

Note: Reciprocal means writing numerator term in denominator and writing denominator term in numerator. Keep in mind that while taking the reciprocal of a fraction you have to change the division sign to multiplication always.