51119554 ÷ 420 
We want to figure out the number of times 51119554 can be divided by 420.

Moving on to step 1:
420 can be fit into 5 0 times, resulting in a remainder of 5.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Grab the next digit (1) from the dividend, add it to 5, then carry on: 51 / 420

Let's proceed to step 2:
420 can be fit into 51 0 times, resulting in a remainder of 51.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 51 leaves us with 51.
Include the next digit (1) from the dividend after 51, then repeat: 511 / 420

On to step 3:
511 divided by 420 is 1 with a remainder of 91.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
Subtracting 420 from 511 leaves us with 91.
Fetch the next digit (1) from the dividend, attach it to 91 and continue: 911 / 420

Moving on to step 4:
The number 420 fits into 911 2 times, leaving a remainder of 71.
The next digit of our result is 2. 
Result so far: 12.0
Subtracting 840 from 911 leaves us with 71.
Fetch the next digit (9) from the dividend, attach it to 71 and continue: 719 / 420

Going ahead to step 5:
420 goes into 719 1 times with a remainder of 299.
Put 1 as the next digit of the answer. 
Result so far: 121.0
The remainder is 299 after subtracting 420 from 719.
Append the next digit (5) from the dividend to 299 and continue with: 2995 / 420

Going ahead to step 6:
420 can be fit into 2995 7 times, resulting in a remainder of 55.
Write down 7 as next digit of the result. 
Result so far: 1217.0
If we take 2940 away from 2995, we end up with 55.
Grab the next digit (5) from the dividend, add it to 55, then carry on: 555 / 420

Going ahead to step 7:
420 can be fit into 555 1 times, resulting in a remainder of 135.
The number 1 becomes the next digit in our result. 
Result so far: 12171.0
Deduct 420 from 555 and we're left with 135.
Bring next digit (4) of the dividend behind the 135 and repeat the process: 1354 / 420

On to step 8:
1354 divided by 420 is 3 with a remainder of 94.
Write down 3 as next digit of the result. 
Result so far: 121713.0
Subtracting 1260 from 1354 leaves us with 94.
Since there are no more digits in the dividend, we add a zero to the remainder making it 940, and continue the process.

Let's proceed to step 9:
420 goes into 940 2 times with a remainder of 100.
Use 2 as the next digit of our solution. 
Result so far: 121713.2
Subtracting 840 from 940 leaves us with 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1000, and continue the process.

Advancing to step 10:
When dividing 1000 by 420, we get 2 with a remainder of 160.
The next digit of our result is 2. 
Result so far: 121713.22
Deduct 840 from 1000 and we're left with 160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1600, and continue the process.

The final outcome is 121713.22, with a leftover of 0.16.