What is the smallest possible value of a + b If a b </mfrac> rounde

Brooke Kramer

Brooke Kramer

Answered question

2022-05-21

What is the smallest possible value of a + b
If a b rounded to the nearest trillionth is 0.008012018027, where a and b are positive integers, what is the smallest possible value of a + b?
I don't see any strategies here for solving this problem, any help? Thanks in advance!

Answer & Explanation

rideonthebussp

rideonthebussp

Beginner2022-05-22Added 10 answers

The continued fraction representations of the limits of the interval are
0.0080120180265 = [ 0 ; 124 , 1 , 4 , 2 , 1 , 463872 , 1 , 1 , 12 , 1 , 1 , 41 ] 0.0080120180275 = [ 0 ; 124 , 1 , 4 , 3 , 545777 , 2 , 13 , 1 , 1 , 1 , 1 , 2 ]
The simplest continued fraction (and therefore also the simplest ordinary fraction!) in that interval is
[ 0 ; 124 , 1 , 4 , 3 ] = 16 1997 = 0.00801201802704056084
and the sum of its numerator and denominator is 2013
(I used Wolfram Alpha to expand the continued fractions fully. For a pencil-and-paper solution one only needs to carry out the expansion until they start differing, which requires only a handful of long divisions with remainder.)
hawwend8u

hawwend8u

Beginner2022-05-23Added 6 answers

1 0.008012018027 = 124.8125000006 0.8125 = 13 16 124.8125 = 1997 16 a + b = 1997 + 16 = 2013

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