Here let us first write the value of each number:
6 thousands means 6*1000=6000.
9 hundreds means 9*100=900.
12 tens means 12*10 =120
10 ones means 10*1 =10
3 tenths means 3/10 =0.3
Now we just have to add all these values to get the final number.
adding 6000 + 900 +120 +10 +0.3 = 7030.3
So the final number is 7030.3