WeBWorK using host: https://webwork.pcc.edu, format: simple, seed: 12, course: orcca

Take a moment to practice adding when at least one negative number is involved. The expectation is that readers can make these calculations here without a calculator.

Add $-1+9\text{.}$

Add $-12+(-98)\text{.}$

Add $100+(-123)\text{.}$

Find the sum $-2.1+(-2.1)\text{.}$

Find the sum $-34.67+81.53\text{.}$

Solution

The two numbers have opposite sign, so we can think to subtract $9-1=8\text{.}$ Of the two numbers we added, the positive is larger, so we stick with postive $8$ as the answer.

The two numbers are both negative, so we can add $12+98=110$ and take the negative of that as the answer: $-110\text{.}$

The two numbers have opposite sign, so we can think to subtract $123-100=23\text{.}$ Of the two numbers we added, the negative is larger, so we take the negative of $23$ as the answer. That is, the answer is $-23\text{.}$

The two numbers are both negative, so we can add $2.1+2.1=4.2$ and take the negative of that as the answer: $-4.2\text{.}$

The two numbers have opposite sign, so we can think to subtract $81.53-34.67=46.86\text{.}$ Of the two numbers we added, the positive is larger, so we stick with postive $46.86$ as the answer.