We must remember that 50 x 2 = 100. Multiplying numbers by 100 would be easier since all we have to do is add two zeros after. For example, 62 x100 = 6200.
Since we multiplied a number by 2, we must divide it by 2 after getting the product. To make this more clearer, for 12 x 50, for example, we have
12 x 50 = (12 x 100)/2 = 1200/2 = 600
Thus, the answer is C.
