Now let's look at the interest during construction, we fill this line in, then the subtotal below will automatically update because we've set that up already. What we want to say is, during the construction period we are not going to have any revenue coming in. How do we know it's a construction period? Because the Capex number up here is bigger than zero.

So if that's the case, we will need to add the interest onto the debt because we have no cash available to pay it. Here's our formula. If the Capex is bigger than zero, so that means we must be in a capital expenditure period or the investment phase of this project. If that's true, we need to work out the interest, the number immediately above D27. That's how much debt we've got at the moment. Zero. But we're going to copy this formula across in a moment, zero times by 5% and if it's not a capital expenditure period, then zero. We are not going to add any interest on.

Let's copy the IDC calculation across and you can see what's happening here. In the second year, we drew 1,300 of debt. We are still in our Capex period, so we haven't got any money to pay the interest. How much interest would we need to pay? 65. That's 5% of the 1,300. Because we haven't got the cash available to pay it, it gets added onto our debt balance, which goes from 1,300 now to 1,365.

1,365 is where we start year three. We draw 500 to pay for the capital expenditure that year and we still are not in a position to pay the interest. So we work out interest now on 1865, what is 1865? It's the amount we've drawn down. 1300 in one year, 500 in another, plus the 65 in interest that was added on last year. Once we're beyond year four or later, then we don't need to add any interest on because we'll be in an operating period and we should have some cash available to pay the interest.

Let's work out the amount we need to repay. Our first repayments are going to be in year five, so what we want to know is what is the debt balance in year five. We could do this using an index match or if you like a lookup formula, I'll use an H lookup. I'd like to look up year five. Where do I want to look it up? I want to look it up here in this first row that has the year numbers and then I want Excel to go down to that row there. Number 29 and Tell me what the corresponding amount of debt is for that year.

We do that by saying Hlookup. Look up C14. That's the fifth year. Look it up in this table. D7 to M29. And when it's found 5 in the top row, we want it to go down all the numbers of rows from 7 down to 29. I could work that out in my head, but I'm going to get Excel to do it for me. Using the rows function, it's just a row counter. Give me the number of rows between 7 and 29 inclusive, so that's gonna be 23 rows. I'm interested in the exact match. Just give me the number for year 5. 1,958.3. That's the amount of debt just before I make my first debt repayment. That's that number there in H29. It's the balance of the debt in year five.