What is 4/10 of 39?

How to calculate 4/10 of 39?

1. Multiply the whole number by the numerator of the fraction: 39 × 4 = 156
2. Divide this result by denominator of the fraction: 156/10 = 15.6
3. Simplify by dividing both the numerator and denominator by their GCD (2):
   • 156/2 = 78
   • 10/2 = 5
4. Which gives: 78/5

Since 78/5 is an improper fraction, the result could also be expressed as a mixed number: 15 3/5

How does it work?

The principle behind finding a fraction of a number, such as 4/10 of 39, is rooted in the method of cross-multiplication.

Consider the following proportion: $\frac{4}{10}=\frac{x}{39}$ (where x represents 4/10 of 39)

1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: $4\times 39=10x$
2. Which gives: $156=10x$
3. Divide both sides by 10 to isolate x: $\frac{156}{10}=\frac{10x}{10}$
4. Which gives the result: $\frac{156}{10}=x$ (or $\frac{78}{5}=x$)

Thus, 4/10 of 39 is equal to 78/5 (or 15.6 in its decimal form).