Add without using number line:
$\left( -380 \right)+\left( -270 \right)$

Hint: Here we have to add the two numbers given without using the number line. Firstly as we know number line is used to add two numbers such that we move on the right side of the first number as many times the value of the second number but here we will follow simple addition and get our desired answer.

Complete step-by-step solution:
We have to find the value of given operation,
$\left( -380 \right)+\left( -270 \right)$
As we can’t use the number line we will simply add the two numbers.
Now as both the numbers are negative it is sure that the answer will also be in negative so we will proceed as follows:
Here we start adding by the unit value first and then proceed to the left values also don’t get confused by the negative sign,
$\begin{align}
  & -380 \\
 & \underline{-270} \\
 & -650 \\
\end{align}$
So we got the value as $-650$
Hence on solving $\left( -380 \right)+\left( -270 \right)$ we get the value as $-650$ .

Note: The four basic arithmetic operators are addition, subtraction, multiplication and division. It is used everywhere in our daily life as well as in any calculation part of any subject. The addition is basically when we take two or more numbers and add them together to get a result. The sign of the bigger number is always the sign of the result we get when we add two numbers. Subtraction is the opposite of addition where we minus one term by another. One thing should be taken in account that if the sign is negative the number which is bigger is treated as smaller due to the negative sign.