What is 30 minus negative 42?

Here we will not only give you the answer to 30 minus negative 42, but also explain how we got the answer.

Start by picturing a number line that goes to negative infinity on the left side of 0 and positive infinity on the right side of 0:

∞ ..... -3, -2, -1, 0, +1, +2, +3, .... ∞

Looking at the number line above, we can make the following observation:

Adding a positive number goes to the right.
Adding a negative number goes to the left.

Adding and subtracting cannot go in the same direction on a number line. Therefore, this must also be true:

Subtracting a positive number goes to the left.
Subtracting a negative number goes to the right.

Thus, with the problem 30 minus negative 42, we are subtracting a negative number and we go to the right. Specifically, we go from +30 to +72 on the number line.

Here is 30 minus negative 42 in mathematical terms with the answer:

30 - (-42) = 72

You may already know that minus minus equals plus or that 30 minus negative 42 is the same as 30 plus 42, but we hope that this page explained the underlying mathematical reason for the answer.

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