21803 ÷ 3 = 7267 R2
We're going to perform division on 21803 with 3 as the divisor.

Step 1:
3 goes into 2 0 times with a remainder of 2.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 2 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 3

Step 2:
3 goes into 21 7 times with a remainder of 0.
Write down 7 as next digit of of the result. 
Result so far: 7
Subtract 21 from 21 to get 0.
Bring next digit (8) of the dividend behind the 0 and repeat the process: 8 / 3

Step 3:
3 goes into 8 2 times with a remainder of 2.
Write down 2 as next digit of of the result. 
Result so far: 72
Subtract 6 from 8 to get 2.
Bring next digit (0) of the dividend behind the 2 and repeat the process: 20 / 3

Step 4:
3 goes into 20 6 times with a remainder of 2.
Write down 6 as next digit of of the result. 
Result so far: 726
Subtract 18 from 20 to get 2.
Bring next digit (3) of the dividend behind the 2 and repeat the process: 23 / 3

Step 5:
3 goes into 23 7 times with a remainder of 2.
Write down 7 as next digit of of the result. 
Result so far: 7267
Subtract 21 from 23 to get 2.

The final result is 7267 with a remainder of 2.