Answer 1

It's a left shift operation..
See this for more clarity..

edit : 𝕱𝖎𝖗𝖊𝖆𝖗𝖒𝖘

int x=5;
x<<=3 => means x=x<<3
x =5 => in binary 00000101
x=x<<3 => after 3 left bit shifts 00101000 = 40
x=40

https://www.sololearn.com/learn/4087/?ref=app

Answer 2

5 is integer. Java allocates 4 bytes for integer so totally, 4*8=32bits each bit store 0 or 1 .
So actually it is in system :
00000000 00000000 00000000 00000101
But just using first multiple of 8 bits for readability...

101 is the value remaining all bits are set 0
Just like a number
0099 is 99 , if there is 4 digit slot, we add 0.

edit:

https://introcs.cs.princeton.edu/java/61data/

Answer 3

Oh. That's complex, I don't think it work. If you run, you get zero only I think. Because int is of 4bytes so its has 4*8=32 bits only.. Maximum you can shift 32 bits.. (value 1928118 is too high)

I added example already in my first post..
x = 5 in binary its value is 00000101
x<<3 means shift 3 bits of x value towards left and zeros will be appended at right

0 0 0 0 0 1 0 1
/ / /
0 0 1 0 1 shifted left
append zeros at right shifted places
0 0 1 0 1 0 0 0

0 0 0 0 0 1 0 1 = 5
/ / /
0 0 1 0 1 0 0 0 = 40
This is equalent to 40 in decimal.

Answer 4

Ex: 25

2 | 25 |
| 12 | 1 //see below comment
| 6 | 0
| 3 | 0
| 1 | 1
| 0 | 1
^
25 in decimal
11001 in binary, (from below to up)

2 | 25 |
| 12 | 1 //here 2 divided by 25 , quotient 12 reminder is 1 => 25/2=12 , 25%2=1

Ex: for 2
2 | 2 |
| 1 | 0
| 0 | 1
^ 10
You can stop this at last you dividend 0.
2 => in binary is 10
Add trailing zeros as much as needed
0000 0010
@ 𝕱𝖎𝖗𝖊𝖆𝖗𝖒𝖘 you can find many online sources, videos on this topic, if it is not clear yet...
hope it helps...

edit:
𝕱𝖎𝖗𝖊𝖆𝖗𝖒𝖘

https://www.cuemath.com/numbers/decimal-to-binary/

https://www.wikihow.com/Convert-from-Decimal-to-Binary

https://introcs.cs.princeton.edu/java/61data/