Closing ratio is the number of deals you close compared to the number of presentations ( or calls ) you make. In this case it means: 1 sale : 3.5 calls ( average ). We will use proportions: 1 : 3.5 = 23 : x. x = 23 * 3.5, x = 80.5. We have to round this number upwards to be more certain that you get the 23 sales. Answer: 81 calls