Accumulated Depreciation

following is a problem:

Machine #: 10
Date of Purchase: 1.11.x1
Original Cost: 1000
Depreciation rate: 10%

a straight line method is used and it is assumed that at the ed of its life, there will a residual value of 10% of the original cost.

a full year’s depreciation is charged in the year of purchase.

what is the accumulated depreciation till dec 31st x5?

*** my problem is that the useful life has not been given so can i compute the annual charge?

annual dep=(cost-Residual value)/useful life
this imples: 900/useful life.

but the useful llife is not given!

thanks for the help