question on vat bad debts

Barney is VAT registered and only makes supplies.On 31 march 2016 he wrote off two irrecoverable debts in his VAT account.The first for £800 (Vat inclusive) was due for payment on 1 june 2015 and despite being chased has still not been paid. The second for £1000(VAT inclusive) relates to a company that Barney has recently been informed has gone into liquidation The debt was due for pyment on 1 December 2015 How much input VAT will Barney be able to recover in respect of the irrecoverable debts in his VAT return for the quarter to 31 March 2016 answer says 1/6*800 how do we get 1/6