Express 0.85 as a fraction?

make sure to multipliy

3 Answers
Feb 19, 2018

See below.

Explanation:

The decimal #0.85# can be converted to the fraction #85/100#, by definition of a decimal. This fraction, #85/100#, however, is not in simplest form. The fraction can be simplified to #17/20#, as both the numerator (top) and denominator (bottom) of the fraction are divisible by 5.

Therefore, your answer is #color(red)(17/20#.

I hope that helps!

Feb 19, 2018

#17/20#

Explanation:

The first step we can take is to put 85 over 100 because #.85# is the same thing as 85 hundredths (we can remember this by noting that there are two decimal places in #.85#, or the numerator, meaning that there are two zeros in the denominator), which is the same thing as #85/100#.

#.85 = 85/100#

We can simplify this by dividing the numerator and denominator by the greatest common factor (in this case, 5).

#85/100 -: 5/5 = 17/20#

17 is a prime number, so there's no way we can simplify this further.

#.85 = 17/20#

Feb 19, 2018

#17/20#

Explanation:

Another way of looking at the decimal of #0.85# is

#ubrace("count of 1's")+ubrace(("some count")/10)+ubrace(("some count")/100)+ubrace(("some count")/1000)+...#
#color(white)("dd.d")darrcolor(white)("dddddddd.d")darrcolor(white)("dddddddddd")darr color(white)("dddddddd.d")darr#
#color(white)("dddd")0color(white)("ddddddddddd")8color(white)("ddddddddddd")5#

So #0.85# is the same as #8/10+5/100#

Multiply by 1 and you do not change the value. However 1 comes in many forms. So write as:

#color(green)([8/10color(red)(xx1)]+5/100)#

#color(green)([8/10color(red)(xx10/10)]+5/100)#

#color(green)(color(white)("dd") [80/100]color(white)("dd")+5/100#

#color(green)((80+5)/100#

#color(green)(85/100)#
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But 5 will divide exactly into both 85 and 100

When dividing or multiplying what you do the top of a fraction you also do to the bottom. In doing so we 'simplify' to an 'equivalent' fraction

#color(green)((85-:5)/(100-:5) -= 17/20#

Where the symbol #-=# means 'equivalent to'