假定每年底还款a万元
年初欠款：10
当年底欠款：10(1+10%),还贷后欠款：10(1+10%)-a；
次年底欠款：[10(1+10%)-a](1+10%),还贷后欠款：10(1+10%)^2-a(1+10%)-a
=10(1+10%)^2-a(1+10%),=
第三年底欠款：[10(1+10%)^2-a(1+10%)-a](1+10%)=10(1+10%)^3-a[(1+10%)^2+(1+10%)],
还贷后欠款：10(1+10%)^3-a[(1+10%)^2+(1+10%)]-a
=10(1+10%)^3-a[(1+10%)^2+(1+10%)+1],方括号内是一个等比数列之和
第六年年底还贷后不再欠款,即：
10(1+10%)^6-a[(1+10%)^5+(1+10%)^4+……+1]=0
10(1+10%)^6 - a [(1+10%)^6-1]/10%
a = 2.296074（万元）= 22960.74元