3.78778777... is an irrational number.
To determine if the number is rational or irrational, we need to know what those terms mean.
Rational numbers are numbers that can be written as a fraction of two integers.
An integer is all natural number, the opposite of those numbers and zero.
Irrational numbers are numbers that cannot be written in fractional form.
Rational numbers are said to be terminating decimals and repeating decimalss.
Now, the number 3.78778777... After the decimal point, we have 787, then another 787, then the next one has 77....
We can see there is no pattern because the last didnt give the same 787 like the previous ones.
Hence, it is an irrational number.