I caught a bit of the Chancellor’s budget speech recently. I try to avoid doing silly things like that, it just makes me angry. However, I was interested to find I was hearing big numbers bandied about without really knowing what was big in the context of a national budget.

So I wondered how I could change that.

My best idea is to scale the numbers down to something I do understand - something like a household budget. There are countless ways to do this, of course, but I ended up going for a nostalgia trip back to the times when I was taking home about £1,200 a month, only partly because it makes the sums easier.

UK plc took in about £600,000,000,000 last year, give or take. My rule of thumb for turning it into a manageable monthly budget is “double the number of billions” - which neatly turns 600 billion into £1,200.

Investing £15 billion in infrastructure, for example, would be similar to putting £30 a month towards DIY projects. Government borrowing of £120 billion is about £240 on the credit card. And Danny Alexander’s £100 million tax loophole swells the coffers to the tune of… oh, 20p or so.

When he talks of GDP, that seems to work out about half of the total revenue (I’d love to hear from an economist about whether that broadly adds up). That means 100% of GDP would be about £600 per month, so 1% of GDP is about £6. Spending 0.7% of GDP on overseas aid is about £4 a month.

To paraphrase Big Ron Atkinson, I never comment on politicians and I’m not going to make an exception for that idiot. This post is simply to help me (and by extension, you) understand the big numbers politicians rattle out and expect you to understand.

Exercise: try matching the numbers to your own monthly or yearly budget and getting an idea for how to listen to Mr Osborne’s.