66121 ÷ 99 
We want to figure out the number of times 66121 can be divided by 99.

Step 1:
6 divided by 99 is 0 with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Append the next digit (6) from the dividend to 6 and continue with: 66 / 99

Advancing to step 2:
66 divided by 99 is 0 with a remainder of 66.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 66 leaves us with 66.
Include the next digit (1) from the dividend after 66, then repeat: 661 / 99

On to step 3:
661 divided by 99 is 6 with a remainder of 67.
The next digit of our result is 6. 
Result so far: 6.0
If we subtract 594 from 661, we get 67.
Take the next digit (2) from the dividend and append it to 67, then repeat: 672 / 99

Step 4:
99 can be fit into 672 6 times, resulting in a remainder of 78.
Put 6 as the next digit of the answer. 
Result so far: 66.0
Deduct 594 from 672 and we're left with 78.
Grab the next digit (1) from the dividend, add it to 78, then carry on: 781 / 99

On to step 5:
781 divided by 99 is 7 with a remainder of 88.
Use 7 as the next digit of our solution. 
Result so far: 667.0
If we subtract 693 from 781, we get 88.
Since there are no more digits in the dividend, we add a zero to the remainder making it 880, and continue the process.

Going ahead to step 6:
When dividing 880 by 99, we get 8 with a remainder of 88.
Use 8 as the next digit of our solution. 
Result so far: 667.8
If we subtract 792 from 880, we get 88.
Since there are no more digits in the dividend, we add a zero to the remainder making it 880, and continue the process.

Moving on to step 7:
880 divided by 99 is 8 with a remainder of 88.
The number 8 becomes the next digit in our result. 
Result so far: 667.88
If we take 792 away from 880, we end up with 88.
Since there are no more digits in the dividend, we add a zero to the remainder making it 880, and continue the process.

The final outcome is 667.88, with a leftover of 0.088.