Step 1:
The first step to converting 3978858590.2218 to a fraction is to re-write 3978858590.2218 in the form p/q where p and q are both positive integers. To start with, 3978858590.2218 can be written as simply 3978858590.2218/1 to technically be written as a fraction.
Step 2:
Next, we will count the number of fractional digits after the decimal point in 3978858590.2218, which in this case is 4. For however many digits after the decimal point there are, we will multiply the numerator and denominator of 3978858590.2218/1 each by 10 to the power of that many digits. So, in this case, we will multiply the numerator and denominator of 3978858590.2218/1 each by 10000:
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 3978858590.2218 as a fraction:
3978858590/1 / 1