12121945 divided by 405 
We're looking to find how many times 405 goes into 12121945.

Going ahead to step 1:
If we divide 1 by 405, we get 0 and a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Append the next digit (2) from the dividend to 1 and continue with: 12 / 405

Going ahead to step 2:
405 goes into 12 0 times with a remainder of 12.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 12 to get 12.
Grab the next digit (1) from the dividend, add it to 12, then carry on: 121 / 405

Step 3:
The number 405 fits into 121 0 times, leaving a remainder of 121.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 121, we get 121.
Include the next digit (2) from the dividend after 121, then repeat: 1212 / 405

Advancing to step 4:
1212 divided by 405 is 2 with a remainder of 402.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Subtract 810 from 1212 to get 402.
Take the next digit (1) from the dividend and append it to 402, then repeat: 4021 / 405

Let's proceed to step 5:
When dividing 4021 by 405, we get 9 with a remainder of 376.
Use 9 as the next digit of our solution. 
Result so far: 29.0
Subtract 3645 from 4021 to get 376.
Bring next digit (9) of the dividend behind the 376 and repeat the process: 3769 / 405

Going ahead to step 6:
When dividing 3769 by 405, we get 9 with a remainder of 124.
Record the quotient 9 as the next digit in the result. 
Result so far: 299.0
Subtracting 3645 from 3769 leaves us with 124.
Include the next digit (4) from the dividend after 124, then repeat: 1244 / 405

Let's proceed to step 7:
When dividing 1244 by 405, we get 3 with a remainder of 29.
The next digit of our result is 3. 
Result so far: 2993.0
Subtract 1215 from 1244 to get 29.
Append the next digit (5) from the dividend to 29 and continue with: 295 / 405

Let's proceed to step 8:
405 can be fit into 295 0 times, resulting in a remainder of 295.
Put 0 as the next digit of the answer. 
Result so far: 29930.0
Subtract 0 from 295 to get 295.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2950, and continue the process.

Step 9:
When dividing 2950 by 405, we get 7 with a remainder of 115.
Record the quotient 7 as the next digit in the result. 
Result so far: 29930.7
Subtracting 2835 from 2950 leaves us with 115.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1150, and continue the process.

Step 10:
405 can be fit into 1150 2 times, resulting in a remainder of 340.
Use 2 as the next digit of our solution. 
Result so far: 29930.72
The remainder is 340 after subtracting 810 from 1150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3400, and continue the process.

Step 11:
3400 divided by 405 is 8 with a remainder of 160.
Write down 8 as next digit of the result. 
Result so far: 29930.728
Subtract 3240 from 3400 to get 160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1600, and continue the process.

Going ahead to step 12:
405 goes into 1600 3 times with a remainder of 385.
The number 3 becomes the next digit in our result. 
Result so far: 29930.7283
Subtract 1215 from 1600 to get 385.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3850, and continue the process.

On to step 13:
3850 divided by 405 is 9 with a remainder of 205.
The next digit of our result is 9. 
Result so far: 29930.72839
If we take 3645 away from 3850, we end up with 205.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2050, and continue the process.

Going ahead to step 14:
405 can be fit into 2050 5 times, resulting in a remainder of 25.
The number 5 becomes the next digit in our result. 
Result so far: 29930.728395
If we subtract 2025 from 2050, we get 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Moving on to step 15:
When dividing 250 by 405, we get 0 with a remainder of 250.
The next digit of our result is 0. 
Result so far: 29930.728395
If we take 0 away from 250, we end up with 250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2500, and continue the process.

On to step 16:
405 can be fit into 2500 6 times, resulting in a remainder of 70.
Record the quotient 6 as the next digit in the result. 
Result so far: 29930.72839506
Subtracting 2430 from 2500 leaves us with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

The final outcome is 29930.72839506, with a leftover of 7e-08.