How to Add & Subtract Distances
Even without a GPS device, adding and subtracting distances can be relatively easy. Consider adding and subtracting distances an extension of simple addition and subtraction learned in elementary school. However, doing the math on your own requires some basic knowledge about the distances to where you are traveling before you start. Add distances when you want to find the total length or distance. Subtract distances when you want to find the unknown distance between two or more more locations whose distances are known. Figuring out the distances between places is a useful trick. For example, whenever you are traveling internationally or trying to figure out how much gas will you need to buy to get to a friend's house, you will need to figure out exact distances between places.
Other People Are Reading
Instructions
-
Adding Distances
-
1
Use a map scale to find the distance between all desired locations. Put your ruler on the first point of location and measure to next location. Record this measurement. Repeat this step for the next location, starting with the second point of location and measuring to the third. Note how long this is. Determine the actual distances by referring to the graphic scale on the map and converting the measured map distances to the actual, real-life distances. Make sure distances are all in the metric or Imperial/USA system.
-
2
Write the first actual distance on a piece of paper. Write the subsequent distances under the first number, properly aligning the each number to the right side of the space. For example, the first distance is 350 feet. The second distance is 34 feet. When you write 34 under 350, make sure the "4" in 34 aligns under the "0" of 350. Write the "3" of 34 under the "5" of 350.
-
-
3
Begin to add the distances. Start from the right to left columns of numbers. In the example given above, the problem would look like:
350
+34
-------
384 -
4
Check your answer again to ensure accuracy. To quickly check your answer, take the sum you got when you added (384) and subtract the smaller number (34), and this should give you the other number in the problem (350).
Subtracting Distances
-
5
Use a map scale to find the distance between all desired locations. Put your ruler on the first point of location and measure to next location. Record this measurement. Repeat this step for the next location, starting with the second point of location and measuring to the third. Note how long this is. Determine the actual distances by referring to the graphic scale on the map and converting the measured map distances to the actual, real-life distances. Make sure distances are all in the metric or Imperial/USA system.
-
6
Write the longest distance on a piece of paper. Write the least subsequent distance under the first number, properly aligning the each number to the right side of the space. For example, the first distance is 100 kilometers. The second distance is 28 kilometers. When you write 28 under 100, make sure the "8" in 28 aligns under the "0" of 100. Write the "2" of 28 under the "0" of 100.
-
7
Begin to subtract the distances. Start from the right to left columns of numbers. In the above example, the problem would look like:
100
- 28
-------
72 -
8
Check your answer again to ensure accuracy. To check this quickly, add the number you got when you subtracted (72) to the smaller of the two numbers (28), and this should add up to the larger number (100).
-
1
Tips & Warnings
If a writing implement and paper can't be found, use the calculator in a cell phone or a calculator to add or subtract the distances.
If time and resources allow, use map websites such as Mapquest.com to find exact distances between two or more locations.
