So may anyone please explain to me what's subtract means?

Ryan$

Junior Member
Joined
Jan 25, 2019
Messages
184
Hi guys, I don't know why but I find it hard sometimes to visualize a subtraction.
I mean lets assume I have 5 zoos - 4 zoos, how many zoos are left, 1 zoo .. but once the question talks about bits in computing world, then for example 20 bits - 4bits, how many bits left? I sometime get stuck three hours on that simply question .... and I think that's because I don't know what subtract means, as a result I must first understand what's the term subtract mean in order to get used by it and manipulate it by problems/question.

So may anyone please explain to me what's subtract means? dont tell me it means subtract two quantity .. I need something more senseable .. thanks alot
 

Otis

Senior Member
Joined
Apr 22, 2015
Messages
1,362
Subtraction is the inverse operation of addition.

💡
 

Dr.Peterson

Elite Member
Joined
Nov 12, 2017
Messages
3,595
We define a - b as the number c such that a = b + c. For example, 20 - 4 is the number x such that 20 = 4 + x, namely 16.
 

Harry_the_cat

Senior Member
Joined
Mar 16, 2016
Messages
1,238
Line up 5 oranges on your kitchen bench. Take 2 away. Now there are 3 on the bench. You have "subtracted" 2 oranges.
 

Ryan$

Junior Member
Joined
Jan 25, 2019
Messages
184
thanks alot
 

Ryan$

Junior Member
Joined
Jan 25, 2019
Messages
184
Hi guys, I already know that almost of the helpers here have known of my problem of subtraction so please take that into consideration and I need to understand, so endure me :) !

lets assume that I have 10 electric polls , which they are numbered from 1 to 10 ! , I was on poll number 1 and each time I'm jumping to the other poll. so if I was on poll number one and I jumped three jumps then 1 + 3 (polls) = 4 , so I'm on poll number 4 ! so now lets assume I want to back two steps so if I do 4-2 then I will be between poll number 2 and poll number 3 so actually I will not go to poll number 2, and that's converse the math which 4-2=2 so I must be on poll 2 .. any help?

what I try to say, when I was on poll number 4 and subtracted two polls, then actually smashed two polls and I'm now between the poll number 2 and poll number 3...not actually on the poll number 2 ... so that's converse to math .. any help? I think I'm not understanding the idea ..
 

Ryan$

Junior Member
Joined
Jan 25, 2019
Messages
184
what's confusing me about subtraction, if I'm on polls number 4 I smashed "analogy" two polls, then I would be on the space between the poll number 2 and poll number 3 .. so it's converse to math which 4-2=2 which I must be on poll number 2
 

Denis

Senior Member
Joined
Feb 17, 2004
Messages
1,689
Take a pill Ryan :geek:
 

Dr.Peterson

Elite Member
Joined
Nov 12, 2017
Messages
3,595
Why between two poles? (That's the spelling you want, by the way.)

Here's jumping 3 steps, from #1 to #4:
Code:
o-->o-->o-->o   o   o   o   o   o   o  ... 1 + 3 = 4
Here's jumping back 2 steps from #4:
Code:
o   o<--o<--o   o   o   o   o   o   o  ... 4 - 2 = 2
Now you're at #2.

Who or what is smashed?
 

Ryan$

Junior Member
Joined
Jan 25, 2019
Messages
184
Why between two poles? (That's the spelling you want, by the way.)

Here's jumping 3 steps, from #1 to #4:
Code:
o-->o-->o-->o   o   o   o   o   o   o  ... 1 + 3 = 4
Here's jumping back 2 steps from #4:
Code:
o   o<--o<--o   o   o   o   o   o   o  ... 4 - 2 = 2
Now you're at #2.

Who or what is smashed?
I mean with "between" like this case:
o o im here o<----o <---o

If you see "im here" means thats im between third and second poll ... Not on #2 poll!!! However i subtract two "back two jumps" and didn't arrive to poll #2..any help?!
 

Dr.Peterson

Elite Member
Joined
Nov 12, 2017
Messages
3,595
Why do you believe you would not be on the pole? You must have some reason for saying this, if you expect us to take you seriously.
 

HallsofIvy

Elite Member
Joined
Jan 27, 2012
Messages
4,938
It's not clear to me why you would think that "20 bits - 4bits" is at all different from "5 zoos - 4 zoos". (Actually, subtracting bits makes a lot more sense to me than subtracting zoos!) Perhaps you are working with a problem where you have to convert from one unit to another: subtract 4 bytes, 7 bits from 9 bytes, 2 bits?

Since 7 bits is larger than 2 bits, "borrow" from the bytes. One byte is 8 bits so "9 bytes, 2 bits" is the same as "8 bytes, 10 bits". Subtracting 4 bytes, 7 bits from 8 bytes, 10 bits is 4 bytes, 3 bits.
 

Otis

Senior Member
Joined
Apr 22, 2015
Messages
1,362

HallsofIvy

Elite Member
Joined
Jan 27, 2012
Messages
4,938
"Pole" or "poll"?
 

Otis

Senior Member
Joined
Apr 22, 2015
Messages
1,362
"Pole" or "poll"?
It's pole, as in 'electric pole' (see post #6).

Dr. Peterson already advised Ryan$ regarding the spelling, but I think Ryan$ is not always willing (or able) to pay attention to replies in their entirety.

😐
 

Ryan$

Junior Member
Joined
Jan 25, 2019
Messages
184
Hi guys, I'm totally by you guys literally succeed to understand what subtraction is and accumulation and whatever arithmetic of math is. there's just one gap I want to close it and by you guys I would be happy to help me.
once I say "50-25" for instance, am I including 25 or excluding 25 in the answer of "50-25" ?! I mean for example lets say I have like this line ------25--------------50 , then I do 50-25 .. am I excluding the point of 25 in the answer of "50-25"? or doesn't it matter including or excluding the number 25/point where 25 is represented ?! thanks alot
 

HallsofIvy

Elite Member
Joined
Jan 27, 2012
Messages
4,938
A single point has no size so, in terms of line segment length, it doesn't matter.

If, instead, you have a line of 50 workers and you count off 25 to be sent to another work site, then, if you count off 25 to stay, the remaining workers, numbers 26 to 50, go to the other work site.

There is a distinct difference between "discrete" problems, where you are counting and "continuous" problems where you are measuring.
 

Otis

Senior Member
Joined
Apr 22, 2015
Messages
1,362
Line up 50 oranges on your kitchen bench. Now take 25 away. How many oranges are left on the bench? Count them.

😎
 

Ryan$

Junior Member
Joined
Jan 25, 2019
Messages
184
Line up 50 oranges on your kitchen bench. Now take 25 away. How many oranges are left on the bench? Count them.

😎
but that's for specific case .
what I'm claiming for example when I solve problems and arrive to number1-number2 what does that mean? for example lets assume while solving problem I faced 7-5 which it's 2, but how I know that 2 is implying/representing discrete case as you stated in your example above, or continuous ?
 
Top