You can tell that his answer is incorrect by analyzing the situation.
A product (In math) is the result of multiplication, or an expression that identifies factors to be multiplied.
To see if the answer is wrong we have to first get the correct product of 78 and 134
78 • 134 = 1,072 + 9,380 = 10,452.
214 is too small of a number. The reason being is that 134 multiplied by any number greater than 1.59701492537 will be greater than 214. 78 is greater than 1.59701492537.
In conclusion, the product of 78 and 134 is not 214.