We haven’t been able to get hold of my sister-in-law for a couple of days. It’s nerve wracking. Soul destroying. I find myself doing horrifying mental arithmetic. I don’t know why, I can’t seem to help it. The UN stated on Thursday that 758 people had been killed. That’s one person for each 2,000 in Gaza. What are the odds that one of them might be Nareman, or one of her family? Xen Hasan writes from the UK. Read more about Phoning my in-laws in Gaza