maths fraction help please...

Question

The number of zeroes coming immediately after the decimal point in the value of (0.2)²⁵  is?

 

 

• 16
• 17
• 18
• none of the above  

   

Have no idea how to even start this one!!!! :( 

Answer 1

Here's another way to think about this:

 

 

 

Remember that 0.2 is 2/10. So:

 

(2/10)²⁵ = 2²⁵/10²⁵ = 2²⁵ × 10^-25 = 33554432. × 10^-25 =

 

Move the decimal in 33554432. to the left 8 places to get:

 

(0.33554432 × 10⁸) × 10^-25 = 0.33554432 × 10^(8-25) = 0.33554432 × 10^-17

 

The 10^-17 means you'll move the decimal to the left 17 places. That will put 17 zeros to the right of the decimal.

Answer 2

Hello Aanchal,

 

(0.2)²⁵ is .2*.2*.2*.2*.2.... 25 times

 

When its done, your answer should be 0.0000000000000000033554432. Now, count the number of zeroes after the decimal point!