Monday to Friday = 5 days

Distance travelled by A in 1 day

Distance travelled by B in 1 day

Total distance travelled by A in 5 days
= $2\times 5=10km$

Total distance travelled by B in 5 days
= $4\times 5=20km$

So, B travels $(20-10)$ km = 10 km more than A from Monday to Friday.

Long division method is not the only way to check if a number is divisible by another number. One can use Divisibility Rules also to check divisibility. 

A number is divisible by 3 if the sum of its digits is divisible by 3.

Sum of the digits of 87 = $8+7=15$

15 is divisible by 3. 
Hence, 87 is also divisible by 3.

A number is divisible by 3 if the sum of its digits is divisible by 3. 

In 5763 sum of the digits is = $5+7+6+3=21$, which is exactly divisible by 3.

So, 5763 is divisible by 3.
A number is divisible by 4 if its last two digits are divisible by 4. The last two digits in 5763 are 63 which is not divisible by 4.
Hence 5763 is not divisible by 4

5763 is not divisible by 6, as it is an odd number. To be divisible by 6, the number should be divisible by both 3 and 2. Only even numbers are divisible by 2. 

A number is divisible by 9 if the sum of its digits is divisible by 9.

In 5763 sum of the digits is = $5+7+6+3=21$, which is not divisible by 9.

So, 5763 is not divisible by 9.
Hence 5763 is divisible by 3.

If 52 is divisible by 4, the next 4th number from 52 should also be divisible by 4.

$\to$ $52+4=56$

 Hence, 56 is also divisible by 4.

Alternate method 

If the last two digits of a number are divisible by 4, then the entire number is divisible by 4.

e.g In 52 last 2 digits are 52 which is divisible by 4.

$\to$ $52÷4=13$ with remainder 0.

Similarly, In 56 last 2 digits are 56 which is divisible by 4.

$\to$ $56÷4=14$ with remainder 0.

Total number of pizzas = $2$

Number of slices in each pizza = $6$

$\therefore$ Total number of slices in both the pizzas = $2\times 6=12$
Number of friends = $3$

Hence, each friend gets $12÷3=4$ slices.

Quotient = 9

Remainder = 1

Multiplication is repeated Addition.

1011 is repeatedly added 9 times = 1011 X 9

$1011\underset{–}{X9}\underset{–}{9099}$

1011 $\times$ 9 = 9099

$137\underset{–}{+05}42$

$119718+\underset{–}{3833}13551$