84210 ÷ 1 = 84210 R0
Alright, let's work through the division of 84210 by 1 step by step.

Step 1:
1 goes into 8 8 times with a remainder of 0.
Write down 8 as next digit of of the result. 
Result so far: 8
Subtract 8 from 8 to get 0.
Bring next digit (4) of the dividend behind the 0 and repeat the process: 4 / 1

Step 2:
1 goes into 4 4 times with a remainder of 0.
Write down 4 as next digit of of the result. 
Result so far: 84
Subtract 4 from 4 to get 0.
Bring next digit (2) of the dividend behind the 0 and repeat the process: 2 / 1

Step 3:
1 goes into 2 2 times with a remainder of 0.
Write down 2 as next digit of of the result. 
Result so far: 842
Subtract 2 from 2 to get 0.
Bring next digit (1) of the dividend behind the 0 and repeat the process: 1 / 1

Step 4:
1 goes into 1 1 times with a remainder of 0.
Write down 1 as next digit of of the result. 
Result so far: 8421
Subtract 1 from 1 to get 0.
Bring next digit (0) of the dividend behind the 0 and repeat the process: 0 / 1

Step 5:
1 goes into 0 0 times with a remainder of 0.
Write down 0 as next digit of of the result. 
Result so far: 84210
Subtract 0 from 0 to get 0.

The final result is 84210 with a remainder of 0.