Answer :

20029293848493
       2832783920
+                1000
--------------------------
20032126633413
an easy way is since there are 2 big numbers and 1 small, add the small to the larger
let's add it to the third number
1,000+2,832,783,920=2,832,784,920
now add 20,029,293,848,493 to 2,832,784,920 (use calculator)
basically you add up the1's  place with the 1's place, 10's place with the 10's place and so on
1's=3+0=3
10's=9+2=11 or 1 and move 1 up to next place
100's=4+9+1=14 or 4 and move 1 up to next place
1,000's= 8+4+1=13 or 3 and move 1 up to next place
10,000's= 4+8+1=13 or 3 and move 1 up to next place
100,000's= 8+7+1=16 or 6 and move 1 up to next place
1,000,000's= 3+2+1=6
10,000,000= 9+3=12 or 2 and move 1 up to next place
100,000,000=2+8+1=11 or 1 and move 1 up to next place
1,000,000,000= 9+2+1=12 or 2 and move 1 up to next place
therer are no more number on the smaller number so just add the bigger ones at the top with the added 1 so
20,032,126,633,413