1. The problem is to find 10% of 78. 2. The formula to find a percentage of a number is: $$\text{Percentage value} = \frac{\text{percentage}}{100} \times \text{total value}$$ 3. Here, the percentage is 10 and the total value is 78. 4. Substitute the values into the formula: $$\frac{10}{100} \times 78$$ 5. Simplify the fraction: $$\frac{\cancel{10}}{\cancel{100}} \times 78 = \frac{1}{10} \times 78$$ 6. Multiply: $$\frac{1}{10} \times 78 = 7.8$$ 7. So, 10% of 78 is 7.8.