# Basic subtraction

1. Mar 2, 2010

### Dav333

how do i do:

8000
-7986
=

i have trouble with multiple zeros, thanks.

2. Mar 2, 2010

### arildno

Well, you have 8 thousands.

You may write that like
$$8000=7000+900+90+10$$
(7 thousands+9 hundreds+9 tens+10 ones)
Thus, we have:
8000-7986=(7000-7000)+(900-900)+(90-80)+(10-6)=0+0+10+4=14

Last edited: Mar 2, 2010
3. Mar 2, 2010

### Dav333

thx. that's a bit over my head. :(

i was looking for the basic way kids do it, like this:

http://img18.imageshack.us/img18/3850/37640968.jpg [Broken]

just when there are zeros together I get confused. thanks.

Last edited by a moderator: May 4, 2017
4. Mar 2, 2010

### arildno

Well, develop your head a bit, then, and make an EFFORT to understand it.

Maths isn't a set of meaningless routines where what you are seeking is a Tutor who can say them in such a way that you memorize it.

5. Mar 2, 2010

### Mentallic

Look at your example. You were trying to find out 8321-4031 but you turned 8321 (8 thousands +3 hundreds +2 tens +1 ones) into (8 thousands + 2 hundreds + 12 tens + 1 ones).

Now, can you try and extend the same idea to break up 8000 in such a way as to solve the subtraction problem? Arildno has the answer, and if you think about what he said, you should be able to apply that idea to the way kids do it.

6. Mar 2, 2010

### Bohrok

The way I learned it years ago:
You move to the left until you get to the first nonzero number from which you can borrow. Cross that number out, subtract 1 from it, and write that number above it (cross out 8 and write 7 above it in your problem). Cross out all the zeros and write 9 above them except for the rightmost 0; that zero gets a 1 before it so it becomes a 10. Then you can subtract each column of numbers.

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