45210 ÷ 9 = 5023 R3
We're going to perform division on 45210 with 9 as the divisor.

Step 1:
9 goes into 4 0 times with a remainder of 4.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 4 to get 4.
Bring next digit (5) of the dividend behind the 4 and repeat the process: 45 / 9

Step 2:
9 goes into 45 5 times with a remainder of 0.
Write down 5 as next digit of of the result. 
Result so far: 5
Subtract 45 from 45 to get 0.
Bring next digit (2) of the dividend behind the 0 and repeat the process: 2 / 9

Step 3:
9 goes into 2 0 times with a remainder of 2.
Write down 0 as next digit of of the result. 
Result so far: 50
Subtract 0 from 2 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 9

Step 4:
9 goes into 21 2 times with a remainder of 3.
Write down 2 as next digit of of the result. 
Result so far: 502
Subtract 18 from 21 to get 3.
Bring next digit (0) of the dividend behind the 3 and repeat the process: 30 / 9

Step 5:
9 goes into 30 3 times with a remainder of 3.
Write down 3 as next digit of of the result. 
Result so far: 5023
Subtract 27 from 30 to get 3.

The final result is 5023 with a remainder of 3.