Step 1:
The first step to converting 70.90171609431 to a fraction is to re-write 70.90171609431 in the form p/q where p and q are both positive integers. To start with, 70.90171609431 can be written as simply 70.90171609431/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 70.90171609431, which in this case is 11. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 70.90171609431/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 70.90171609431/1 each by 100000000000:
Step 3:
Now the last step is to simplify the fraction (if possible) by finding similar factors and cancelling them out, which leads to the following answer for 70.90171609431 as a fraction:
12266/173 / 1