To input/change the figures please use working file. I suggest that you use the pivot to see items only and then sort it by biggest sales. Then choose the items that you sell most and focus with the review on those first. Most likely you have about 80% of the sales. Review those items by customers and make best estimation. At this point it is important we get the top products and the top customers right. I would not spend much time on the smaller amounts unless you delete the sales or add new sales. You can try calling me on my mobile tomorrow 087 129 4545.