How do u turn this 3.78 into a fraction

That can be read as 3 and 78 one-hundreths meaning it would look like this:

3 78/100

which is simplified to 3 39/50.

if you want an improper fraction you take the denominator and multiply it by the whole number then add the numerator and put it over the original denominator:

50 (3) = 150 + 39 = 189 / 50

which cant be simplified further

1) 3.78 = 3.78/1

2) Consider 3.78/1 and multiply numerator and denominator by 100:

3.78x100) / (1x100) = 378/100

3) Simplify 378/100 → (GCD or GCF = 2) → 189/50

Then 3.78 = 189/50