21378651 ÷ 623 
Our goal is to divide 21378651 by 623.

Advancing to step 1:
The number 623 fits into 2 0 times, leaving a remainder of 2.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 2, we end up with 2.
Grab the next digit (1) from the dividend, add it to 2, then carry on: 21 / 623

Advancing to step 2:
If we divide 21 by 623, we get 0 and a remainder of 21.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 21 leaves us with 21.
Append the next digit (3) from the dividend to 21 and continue with: 213 / 623

Going ahead to step 3:
623 goes into 213 0 times with a remainder of 213.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 213 leaves us with 213.
Grab the next digit (7) from the dividend, add it to 213, then carry on: 2137 / 623

Let's proceed to step 4:
623 can be fit into 2137 3 times, resulting in a remainder of 268.
Use 3 as the next digit of our solution. 
Result so far: 3.0
Subtracting 1869 from 2137 leaves us with 268.
Grab the next digit (8) from the dividend, add it to 268, then carry on: 2688 / 623

Step 5:
623 goes into 2688 4 times with a remainder of 196.
Write down 4 as next digit of the result. 
Result so far: 34.0
If we take 2492 away from 2688, we end up with 196.
Grab the next digit (6) from the dividend, add it to 196, then carry on: 1966 / 623

On to step 6:
If we divide 1966 by 623, we get 3 and a remainder of 97.
The number 3 becomes the next digit in our result. 
Result so far: 343.0
If we take 1869 away from 1966, we end up with 97.
Include the next digit (5) from the dividend after 97, then repeat: 975 / 623

Advancing to step 7:
When dividing 975 by 623, we get 1 with a remainder of 352.
The number 1 becomes the next digit in our result. 
Result so far: 3431.0
Deduct 623 from 975 and we're left with 352.
Bring next digit (1) of the dividend behind the 352 and repeat the process: 3521 / 623

Step 8:
When dividing 3521 by 623, we get 5 with a remainder of 406.
Write down 5 as next digit of the result. 
Result so far: 34315.0
Subtract 3115 from 3521 to get 406.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4060, and continue the process.

Step 9:
If we divide 4060 by 623, we get 6 and a remainder of 322.
Write down 6 as next digit of the result. 
Result so far: 34315.6
Subtracting 3738 from 4060 leaves us with 322.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3220, and continue the process.

Moving on to step 10:
The number 623 fits into 3220 5 times, leaving a remainder of 105.
Put 5 as the next digit of the answer. 
Result so far: 34315.65
The remainder is 105 after subtracting 3115 from 3220.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1050, and continue the process.

Step 11:
If we divide 1050 by 623, we get 1 and a remainder of 427.
Use 1 as the next digit of our solution. 
Result so far: 34315.651
The remainder is 427 after subtracting 623 from 1050.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4270, and continue the process.

Moving on to step 12:
When dividing 4270 by 623, we get 6 with a remainder of 532.
The number 6 becomes the next digit in our result. 
Result so far: 34315.6516
Deduct 3738 from 4270 and we're left with 532.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5320, and continue the process.

Step 13:
If we divide 5320 by 623, we get 8 and a remainder of 336.
Use 8 as the next digit of our solution. 
Result so far: 34315.65168
If we subtract 4984 from 5320, we get 336.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3360, and continue the process.

On to step 14:
The number 623 fits into 3360 5 times, leaving a remainder of 245.
Put 5 as the next digit of the answer. 
Result so far: 34315.651685
Subtracting 3115 from 3360 leaves us with 245.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2450, and continue the process.

Let's proceed to step 15:
623 goes into 2450 3 times with a remainder of 581.
Use 3 as the next digit of our solution. 
Result so far: 34315.6516853
The remainder is 581 after subtracting 1869 from 2450.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5810, and continue the process.

Let's proceed to step 16:
The number 623 fits into 5810 9 times, leaving a remainder of 203.
Use 9 as the next digit of our solution. 
Result so far: 34315.65168539
Deduct 5607 from 5810 and we're left with 203.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2030, and continue the process.

The final outcome is 34315.65168539, with a leftover of 2.03e-07.