An aging analysis of Ceradyne Limited's accounts receivable at December 31, 2021 and 2020, showed the following: Number of Days Accounts Receivable. Estimated Outstanding 2021 2020 Percentage Uncollectible 0-30 days $301,300 $319,700 3% 31-60 days 64,300 114,900 6% 61-90 days 85,900 76,300 12% Over 90 days 131,200 50,500 24% Total $582,700 $561,400 Additional information: 1. At December 31, 2020, the unadjusted balance in Allowance for Doubtful Accounts was a credit of $8,500. 2. In 2021, $42.100 of accounts were written off as uncollectible and $2,900 of accounts previously written off were recovered.