Three numbers I won't run a P&L without.

I've been a CFO at three different companies and I've learned to never run a P&L without three numbers in the corner of the page. None of them are line items. They're just there to keep me honest.

The first is gross margin trended over six quarters, not the current quarter. A single point of gross margin is almost meaningless; the slope tells you whether the business is improving its economics or just adding revenue. I've watched boards celebrate a record quarter in absolute terms while the underlying margin trended down for two years. The headline number can hide a lot.

The second is cash conversion — operating cash flow divided by reported operating profit. If that number is much below one for more than a quarter or two, your profit is an accounting story rather than an economic one. It usually means working capital is funding the apparent growth, and that runway is finite.

The third is the share of revenue from your top ten customers. Not as a static figure, but compared to the same number a year ago. A business that grows by adding one large customer per year looks like growth on the headline and reads as concentration risk in this number. Both are true, but only one of them is the future.

None of these belong inside the P&L. They belong in the margin of the page, watching it. Without them I find I make decisions at the speed of the headline and regret them at the speed of the underlying.