If 700- 600 = x, x = 600 = 700
If you calculated x - y = z then calculate z + y. If the answer is x your calculation is fine. If not, one of the sums went wrong.
The inverse operation of addition would be subtraction. The inverse operation of subtraction would be addition. The inverse operation of multiplication is division and the inverse operation of division is multiplication. It is called the inverse operation because you are reversing the equation. If you add, subtract, multiply, or divide the same number on each side of the equation, then the equation would still be true. As long as you are doing the same thing on BOTH side of the equation. The reciprocal is used for dividing fractions. All you have to do for finding the reciprocal of a fraction is flip the fraction. Ex: The reciprocal of 1/4 is 4. The reciprocal of 5/8 is 8/5. You can check by multiplying the two fractions. It will equal to one if you did it right. I hope this helped a little bit.
I think they invented it to do bigger mathscales, and to check multiplication because they are inverse operations.
Consider the main operations to be addition and multiplication. In that case, subtraction is defined in terms of addition, for example, a - b = a + (-b) (where the last "-b" refers to the additive inverse of b), while a / b = a times 1/b (where 1/b is the multiplicative inverse of b). Now, assuming that commutative, etc. properties hold for addition and multiplication, check what happens with a subtraction. That should clarify everything. For example: a - b = a + (-b) whereas: b - a = b + (-a) which happens NOT to be the same as a - b, but rather its additive inverse.
If you have calculated A + B = C then you can calculate C - A. If the answer is B then the first sum is correct.
If the problem is 6+8=14 you can subtract either 6 OR 8 from 14 and you will get the other answer .14-6=8
You don't. You can check addition with subtraction or subtraction with addition, since subtraction is the opposite of addition. Similary, you can check division with multiplication, or vice versa.
Subtraction is used to check addition.
Addition is the opposite of subtraction. For example, 24 - 9 = 15. If you want to check your answer, add 9 + 15. It equals 24, so your answer is correct.
Add the result of the subtraction to the number you were subtracting and you should get the number from which you subtracted. example 246.8 - 35.15 = 211.65 To check add 211.65 + 35.15 and see if you get 246.8
The inverse of add 7 is minus 7 Example: 20+7=27 to check do... 27-7=20
Check out the acos function.