HS Equation

HS manufactures components for use in computers. The business operates in a highly
competitive market where there are a large number of manufacturers of similar
components. HS is considering its pricing strategy for the next 12 weeks for one of its
components. The Managing Director seeks your advice to determine the selling price that
will maximise the profit to be made during this period.
You have been given the following data:
Market demand
The current selling price of the component is $1,350 and at this price the average weekly
demand over the last four weeks has been 8,000 components. An analysis of the market
shows that, for every $50 increase in selling price, the demand reduces by 1,000
components per week. Equally, for every $50 reduction in selling price, the demand
increases by 1,000 components per week.
Costs
The direct material cost of each component is $270. This price is part of a fixed price
contract with the material suppliers and the contract does not expire for another year.
Production labour and conversion costs, together with other overhead costs and the
corresponding output volumes, have been collected for the last four weeks and they are as
follows:
Week Output volume (units) $000
1 9,400 7,000
2 7,600 5,688
3 8,500 6,334
4 7,300 5,446
No significant changes in cost behaviour are expected over the next 12 weeks.

The question above is being taken from the kaplan kit.I understand all other aspects of the question which includes solving the equation P=a-bq.But i got struck at the high low part where we have to calculate the variable cost per unit.As you can see the variable cost per unit is 1554/2100=0.74 but why in the kit solution the variable cost was multiplied by 1000 units? It was
$(7,000 – 5,446) × 1,000 / (9,400 – 7,300)
= $1,554 × 1,000 / 2,100
= $740.
Later we have to add $270 in the variable cost to get the full variable cost per component but why we have to multiply 0.74 by 1000 ? Why the total variable costs should be $1010 instead of $270.74 ?