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Subtraction is the exact opposite of addition. It basically means that you have a certain number of objects, and some of them are about to be taken away from you. How much will you be left with?
This is illustrated below in the following diagram.
| O O O O O | O O O O | O | ||
| take away | equals |
Now if you added the "amount that you are left with" to the "amount that you took away," the result should equal the amount that you started with.
In this case if you added 1 (the amount that we are left with) to 4 (the amount that we took away), the result should be 5 (the amount that we started with).
1 + 5 = 6
Here is another example of subtraction.
| O O O O O O O | O O O | O O O O | ||
| take away | equals |
Now if you added the "amount that you are left with" to the "amount that you took away," the result should equal the amount that you started with.
In this case if you added 4 (the amount that we are left with) to 3 (the amount that we took away), the result should be 7 (the amount that we started with).
4 + 3 = 7
Rather than continually count every time you want to subtract items, we have definite rules establishing the difference of numbers. You will find all of these rules in the subtraction table.
Examine the following table
Study it!
Drill yourself on it.
Quiz yourself on it using flash cards that you either bought or made yourself.
Commit it to memory.
| 0-0=0 since 0+0=0 |
1-0=1 since 1+O=1 |
2-0=2 since 2+0=2 |
3-0=3 since 3+0=3 |
4-0=4 since 4+0=4 |
5-0=5 since 5+0=5 |
6-0=6 since 6+0=6 |
7-0=7 since 7+0=7 |
8-0=8 since 8+0=8 |
9-0=9 since 9+0=9 |
10-0=10 since 10+0=10 |
| 1-1=0 since 0+1=1 |
2-1=1 since 1+1=2 |
3-1=2 since 2+1=3 |
4-1=3 since 3+1=4 |
5-1=4 since 4+1=5 |
6-1=5 since 5+1=6 |
7-1=6 since 6+1=7 |
8-1=7 since 7+1=8 |
9-1=8 since 8+1=9 |
10-1=9 since 9+1=10 |
11-1=10 since 10+1=11 |
| 2-2=0 since 0+2=2 |
3-2=1 since 1+2=3 |
4-2=2 since 2+2=4 |
5-2=3 since 3+2=5 |
6-2=4 since 4+2=6 |
7-2=5 since 5+2=7 |
8-2=6 since 6+2=8 |
9-2=7 since 7+2=9 |
10-2=8 since 8+2=10 |
11-2=9 since 9+2=11 |
12-2=10 since 10+2=12 |
| 3-3=0 since 0+3=3 |
4-3=1 since 1+3=4 |
5-3=2 since 2+3=5 |
6-3=3 since 3+3=6 |
7-3=4 since 4+3=7 |
8-3=5 since 5+3=8 |
9-3=6 since 6+3=9 |
10-3=7 since 7+3=10 |
11-3=8 since 8+3=11 |
12-3=9 since 9+3=12 |
13-3=10 since 10+3=13 |
| 4-4=0 since 0+4=4 |
5-4=1 since 1+4=5 |
6-4=2 since 2+4=6 |
7-4=3 since 3+4=7 |
8-4=4 since 4+4=8 |
9-4=5 since 5+4=9 |
10-4=6 since 6+4=10 |
11-4=7 since 7+4=11 |
12-4=8 since 8+4=12 |
13-4=9 since 9+4=13 |
14-4=10 since 10+4=14 |
| 5-5=0 since 0+5=5 |
6-5=1 since 1+5=6 |
7-5=2 since 2+5=7 |
8-5=3 since 3+5=8 |
9-5=4 since 4+5=9 |
10-5=5 since 5+5=10 |
11-5=6 since 6+5=11 |
12-5=7 since 7+5=12 |
13-5=8 since 8+5=13 |
14-5=9 since 9+5=14 |
15-5=10 since 10+5=15 |
| 6-6=0 since 0+6=6 |
7-6=1 since 1+6=7 |
8-6=2 since 2+6=8 |
9-6=3 since 3+6=9 |
10-6=4 since 4+6=10 |
11-6=5 since 5+6=11 |
12-6=6 since 6+6=12 |
13-6=7 since 7+6=13 |
14-6=8 since 8+6=14 |
15-6=9 since 9+6=15 |
16-6=10 since 10+6=16 |
| 7-7=0 since 0+7=7 |
8-7=1 since 1+7=8 |
9-7=2 since 2+7=9 |
10-7=3 since 3+7=10 |
11-7=4 since 4+7=11 |
12-7=5 since 5+7=12 |
13-7=6 since 6+7=13 |
14-7=7 since 7+7=14 |
15-7=8 since 8+7=15 |
16-7=9 since 9+7=16 |
17-7=10 since 10+7=17 |
| 8-8=0 since 0+8=8 |
9-8=1 since 1+8=9 |
10-8=2 since 2+8=10 |
11-8=3 since 3+8=11 |
12-8=4 since 4+8=12 |
13-8=5 since 5+8=13 |
14-8=6 since 6+8=14 |
15-8=7 since 7+8=15 |
16-8=8 since 8+8=16 |
17-8=9 since 9+8=17 |
18-8=10 since 10+8=18 |
| 9-9=0 since 0+9=9 |
10-9=1 since 1+9=10 |
11-9=2 since 2+9=11 |
12-9=3 since 3+9=12 |
13-9=4 since 4+9=13 |
14-9=5 since 5+9=14 |
15-9=6 since 6+9=15 |
16-9=7 since 7+9=16 |
17-9=8 since 8+9=17 |
18-9=9 since 9+9=18 |
19-9=10 since 10+9=19 |
| 10-10=0 since 0+10=10 |
11-10=1 since 1+10=11 |
12-10=2 since 2+10=12 |
13-10=3 since 3+10=13 |
14-10=4 since 4+10=14 |
15-10=5 since 5+10=15 |
16-10=6 since 6+10=16 |
17-10=7 since 7+10=17 |
18-10=8 since 8+10=18 |
19-10=9 since 9+10=19 |
20-10=10 since 10+10=20 |
Now you try your hand at subtracting. Click on the "generate a problem" button to see your problem. Place your answer in the text boxt and then click the "check my answer" button. You'll be told whether or not your answer was correct.
After you finish the problem, click on the "reset" button and then click the "generate a problem" button to see another problem. Keep on generating problems until you feel confortable with subtraction.