Subtraction of Numbers using Number Line

Subtraction of numbers using number line will help us to learn how a number line can be used for subtracting one number from the another number.

Subtraction of numbers can be well understood with the help of the number line.

Keep in mind the following rules of movements on the number line to subtract a given number from another number:

(i) Mark both the given numbers on the same number line, each starting from zero.

(ii) From the second number (i.e., the one which is to be subtracted), find how many steps are needed to reach the position of the first number.

This number of steps is the required answer.

Note:

(i) If the number of steps moved is towards right, the answer is a positive number.

(ii) If the number of steps moved is towards left, the answer is a negative number.

Subtraction of numbers using number line in different situation:

1. Subtraction of a positive number from a positive number.

For example: Evaluate using a number line (+6) – (+2).

Mark the positions of numbers +6 and +2 on the same number line.

Now count how many steps are needed from the position of number +2 to reach the position of number +6. We find it is 4 steps to the right.

Therefore, (+6) – (+2) = +4 or simply 4.

2. Subtraction of a negative number from a positive number.

For example: Evaluate using a number line (+5) – (-3).

Mark the position of numbers +5 and -3 on the same number line.

Now starting from the position of -3, count the number of steps needed to reach +5. Also see the direction. We find, we have to move 8 steps to the right.

Therefore, (+5) – (-3) = +8

3. Subtraction of a positive number from a negative number.

For example: Evaluate using a number line (-7) – (+2).

After marking the position of -7 and +2 on the same number line, count from the position of +2 the number steps and the direction needed to reach -7.

We find that there are 9 steps to the left.

Therefore, (-7) – (+2) = -9

4. Subtraction of a negative number from a negative number.

For example: Evaluate using a number line (-6) – (-4).

Mark the position of numbers -6 and -4 on the same number line.

Now count how many steps are needed from the position of number -4 to reach the position of number -6. We find it is 2 steps to the left.

Therefore, (-6) – (-4) = -2

Subtraction of Whole Numbers on Number Line

The subtraction of two whole numbers can also be shown on a number line.

1. Let us find 8 - 5.

The point at the tip of the longest arrow is 8. Start from 8. Since 5 is being subtracted, move towards left with one jump of 1 unit, Make 5 such jumps. We reach at the point 3. Hence, 8-5-3

2. Using the number line, write the whole number which is obtained when 4 is subtracted from 9.

To find 9-4, start from 9 and go 4 units to the left to obtain 5, as shown in the following figure.

Hence, 9 - 4 = 5

6th Grade Math Practice

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