Add Rational Numbers on Number Line

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7th Grade Math › Add Rational Numbers on Number Line

Questions 1 - 10
1

On a number line, start at $3$ and add $5$. You move a distance of $|5|$ units in the direction of the sign of $5$. Where do you end up (what is $3+5$)?

Start at 3, move right 3 units, end at $6$.

Start at 3, move left 5 units, end at $-2$.

Start at 0, move right 5 units, end at $5$.

Start at 3, move right 5 units, end at $8$.

Explanation

This question tests interpreting p + q on a number line: start at p=3, move distance |q|=|5|=5 units in the direction determined by the sign of q=5 (right if positive, left if negative), ending at p+q=8. Number line addition: locate starting position p=3 (can be positive, negative, or zero), identify distance to move |q|=5 (magnitude of q: |-4|=4 units, |5|=5 units regardless of sign), determine direction from sign of q (if q>0 move right toward larger numbers, if q<0 move left toward smaller), land at p+q=8. For example, -3 + (-6) starts at -3, adding -6 moves left 6 units (negative addition moves left), ending at -9 (farther left/more negative); or 2+5 starts at 2, moves right 5, ends at 7; or -5+8 starts at -5, moves right 8, crosses zero to end at +3. The correct interpretation is starting at position 3, moving a distance of 5 units to the right (since 5 is positive), and ending at the final position of 8. A common error is choosing the wrong direction, like moving left for a positive addition (as in choice A, ending at -2), or starting at the wrong position like 0 instead of 3 (choice B), or moving the wrong distance like 3 units instead of 5 (choice D). The process is: (1) locate p=3 on the number line (mark starting position), (2) determine |q|=5 distance, (3) determine direction (q positive→right), (4) move from p right 5 units, (5) mark final position at 8 (p+q result). Sign rules: adding positive increases (moves right on number line to larger), adding negative decreases (moves left to smaller); contexts reinforce: deposit (+) moves balance right (increases), withdrawal (-) moves left (decreases), temperature rise (+) moves right (warmer), fall (-) moves left (cooler).

2

On a number line, start at $7$ and add $-4$. Describe the movement and the final position (the value of $7+(-4)$).

Start at 7, move left $-4$ units, end at $11$.

Start at 7, move right 4 units, end at $11$.

Start at 0, move left 4 units, end at $-4$.

Start at 7, move left 4 units, end at $3$.

Explanation

This question tests interpreting p + q on a number line: start at p=7, move distance |q|=|-4|=4 units in the direction determined by the sign of q=-4 (right if positive, left if negative), ending at p+q=3. Number line addition: locate starting position p=7 (can be positive, negative, or zero), identify distance to move |q|=4 (magnitude of q: |-4|=4 units, |5|=5 units regardless of sign), determine direction from sign of q (if q>0 move right toward larger numbers, if q<0 move left toward smaller), land at p+q=3. Example: 7+(-4) starts at 7 (p=7), moves left 4 units (q=-4, distance=4, direction=left), ends at 3 (7-4=3, or thinking: 7 is 4 more than 3, moving left 4 from 7 reaches 3); context: temperature -5°C rises 8° (adds +8): start -5, move right 8 units (positive rise), end at 3°C (-5+8=3). The correct interpretation is starting at position 7, moving a distance of 4 units to the left (since -4 is negative), and ending at the final position of 3. A common error is choosing the wrong direction, like moving right for a negative addition (as in choice B, ending at 11), or starting at the wrong position like 0 instead of 7 (choice C), or treating distance as signed like moving '-4 units' to the left interpreted as right (choice D). The process is: (1) locate p=7 on the number line (mark starting position), (2) determine |q|=4 distance, (3) determine direction (q negative→left), (4) move from p left 4 units, (5) mark final position at 3 (p+q result). Sign rules: adding positive increases (moves right on number line to larger), adding negative decreases (moves left to smaller); mistakes: direction from sign confused (most common error: thinking negative addition moves right), distance as signed quantity (using -4 as distance when should use 4).

3

Which statement correctly describes adding $-\tfrac{3}{4}$ to $\tfrac{1}{2}$ on a number line, and gives the correct final value?

Start at $\tfrac{1}{2}$, move right $\tfrac{3}{4}$, end at $\tfrac{5}{4}$.

Start at $\tfrac{1}{2}$, move left $-\tfrac{3}{4}$, end at $\tfrac{5}{4}$.

Start at $-\tfrac{3}{4}$, move left $\tfrac{1}{2}$, end at $-\tfrac{5}{4}$.

Start at $\tfrac{1}{2}$, move left $\tfrac{3}{4}$, end at $-\tfrac{1}{4}$.

Explanation

This question tests interpreting p + q on a number line: start at p=1/2, move distance |q|=|-3/4|=3/4 units in the direction determined by the sign of q=-3/4 (right if positive, left if negative), ending at p+q=-1/4. Number line addition: locate starting position p=1/2 (can be positive, negative, or zero), identify distance to move |q|=3/4 (magnitude of q: |-4|=4 units, |5|=5 units regardless of sign), determine direction from sign of q (if q>0 move right toward larger numbers, if q<0 move left toward smaller), land at p+q=-1/4. For example, -3 + (-6) starts at -3, adding -6 moves left 6 units (negative addition moves left), ending at -9 (farther left/more negative); or 2+5 starts at 2, moves right 5, ends at 7; or -5+8 starts at -5, moves right 8, crosses zero to end at +3. The correct interpretation is starting at position 1/2, moving a distance of 3/4 units to the left (since -3/4 is negative), and ending at the final position of -1/4. A common error is choosing the wrong direction, like moving right for a negative addition (as in choice A, ending at 5/4), or starting at the wrong position like -3/4 instead of 1/2 (choice B), or treating distance as signed like moving '-3/4 units' to the left interpreted as right (choice D). The process is: (1) locate p=1/2 on the number line (mark starting position), (2) determine |q|=3/4 distance, (3) determine direction (q negative→left), (4) move from p left 3/4 units, (5) mark final position at -1/4 (p+q result). Sign rules: adding positive increases (moves right on number line to larger), adding negative decreases (moves left to smaller); mistakes: direction from sign confused (most common error: thinking negative addition moves right), distance as signed quantity (using -3/4 as distance when should use 3/4).

4

On a number line, start at $3$ and add $5$. You move a distance of $|5|$ units in the direction of the sign of $5$. Where do you end up (what is $3+5$)?​

Start at $3$, move right $5$ units, end at $8$.

Start at $3$, move left $5$ units, end at $-2$.

Start at $5$, move right $3$ units, end at $8$.

Start at $0$, move right $5$ units, end at $5$.

Explanation

This question tests interpreting p + q on a number line: start at p=3, move distance |q|=|5|=5 units in the direction determined by the sign of q=5 (right if positive, left if negative), ending at p+q=8. Number line addition involves locating the starting position p=3 (positive, to the right of zero), identifying the distance to move |q|=5 (magnitude regardless of sign), determining the direction from the sign of q (positive, so move right toward larger numbers), and landing at 8. For example, like 7 + (-4) starts at 7, moves left 4 units, ends at 3; in a context, if temperature is -5°C and rises 8° (adds +8), start at -5, move right 8 units, end at 3°C. Another example: -3 + (-6) starts at -3, moves left 6 units, ends at -9; or 2 + 5 starts at 2, moves right 5, ends at 7; or -5 + 8 starts at -5, moves right 8, ends at 3. The correct interpretation is starting at 3, moving right 5 units (since 5 is positive), ending at 8, which matches choice C. A common error is moving in the wrong direction, like left for positive addition, or starting at the wrong position such as 0 or switching p and q. The process is: (1) locate p=3 on the number line, (2) determine |q|=5 distance, (3) determine direction (positive → right), (4) move right 5 from 3, (5) mark final position at 8; remember, adding positive increases the value (moves right), while adding negative decreases it (moves left).

5

A hiker is at an elevation of $2.5$ meters relative to a reference point. The hiker then goes down $3.2$ meters. On a number line, this is $2.5+(-3.2)$. What is the final elevation?

$5.7$ meters (start at 2.5, move right 3.2).

$0.7$ meters (start at 2.5, move left 1.8).

$-5.7$ meters (start at 0, move left 5.7).

$-0.7$ meters (start at 2.5, move left 3.2).

Explanation

This question tests interpreting p + q on a number line: start at p=2.5, move distance |q|=|-3.2|=3.2 units in the direction determined by the sign of q=-3.2 (right if positive, left if negative), ending at p+q=-0.7. Number line addition: locate starting position p=2.5 (can be positive, negative, or zero), identify distance to move |q|=3.2 (magnitude of q: |-4|=4 units, |5|=5 units regardless of sign), determine direction from sign of q (if q>0 move right toward larger numbers, if q<0 move left toward smaller), land at p+q=-0.7. For example, -3 + (-6) starts at -3, adding -6 moves left 6 units (negative addition moves left), ending at -9 (farther left/more negative); or 2+5 starts at 2, moves right 5, ends at 7; or -5+8 starts at -5, moves right 8, crosses zero to end at +3. The correct interpretation is starting at position 2.5, moving a distance of 3.2 units to the left (since going down is -3.2, negative), and ending at the final position of -0.7 meters. A common error is choosing the wrong direction, like moving right for a negative change (as in choice A, ending at 5.7), or moving the wrong distance like 1.8 units (choice C), or starting at the wrong position like 0 (choice D). The process is: (1) locate p=2.5 on the number line (mark starting position), (2) determine |q|=3.2 distance, (3) determine direction (q negative→left), (4) move from p left 3.2 units, (5) mark final position at -0.7 (p+q result). Sign rules: adding positive increases (moves right on number line to larger), adding negative decreases (moves left to smaller); contexts reinforce: elevation increase (+) moves right (higher), decrease (-) moves left (lower); mistakes: direction from sign confused.

6

A video game character is at position $-5$ on a number line. The character moves $+8$ units. Using number line addition, what is the final position (what is $-5+8$)?

Start at $-5$, move right 8 units, end at $3$.

Start at $-5$, move right 5 units, end at $0$.

Start at $-5$, move left 8 units, end at $-13$.

Start at $8$, move right 5 units, end at $13$.

Explanation

This question tests interpreting p + q on a number line: start at p=-5, move distance |q|=|8|=8 units in the direction determined by the sign of q=8 (right if positive, left if negative), ending at p+q=3. Number line addition: locate starting position p=-5 (can be positive, negative, or zero), identify distance to move |q|=8 (magnitude of q: |-4|=4 units, |5|=5 units regardless of sign), determine direction from sign of q (if q>0 move right toward larger numbers, if q<0 move left toward smaller), land at p+q=3. For example, -3 + (-6) starts at -3, adding -6 moves left 6 units (negative addition moves left), ending at -9 (farther left/more negative); or 2+5 starts at 2, moves right 5, ends at 7; or -5+8 starts at -5, moves right 8, crosses zero to end at +3. The correct interpretation is starting at position -5, moving a distance of 8 units to the right (since +8 is positive), and ending at the final position of 3. A common error is choosing the wrong direction, like moving left for a positive addition (as in choice A, ending at -13), or starting at the wrong position like 8 instead of -5 (choice C), or moving the wrong distance like 5 units instead of 8 (choice D). The process is: (1) locate p=-5 on the number line (mark starting position), (2) determine |q|=8 distance, (3) determine direction (q positive→right), (4) move from p right 8 units, (5) mark final position at 3 (p+q result). Sign rules: adding positive increases (moves right on number line to larger), adding negative decreases (moves left to smaller); contexts reinforce: deposit (+) moves balance right (increases), withdrawal (-) moves left (decreases), temperature rise (+) moves right (warmer), fall (-) moves left (cooler).

7

Determine the distance and direction for the addition $-6+(-2)$. On a number line, you start at $-6$ and add $-2$. Which description is correct, and what is the final position?

Move left $-2$ units to $-8$.

Move right $2$ units to $-4$.

Move left $2$ units to $-8$.

Move right $6$ units to $0$.

Explanation

This question tests interpreting p + q on a number line: start at p=-6, move distance |q|=|-2|=2 units in the direction determined by the sign of q=-2 (right if positive, left if negative), ending at p+q=-8. Number line addition involves locating the starting position p=-6, identifying the distance to move |q|=2 (magnitude, not negative), determining the direction from the sign of q (negative, so move left), and landing at -8. For example, 7 + (-4) starts at 7, moves left 4 units, ends at 3; in a context, if temperature is -5°C and rises 8° (adds +8), start at -5, move right 8 units, end at 3°C. Another example: -3 + (-6) starts at -3, moves left 6 units, ends at -9; or -6 + (-2) starts at -6, moves left 2, ends at -8. The correct description is moving left 2 units to -8, which matches choice C. A common error is treating distance as -2 (confusing signed distance) or moving right. The process is: (1) locate p=-6, (2) determine |q|=2 distance, (3) determine direction (negative → left), (4) move left 2 from -6, (5) mark final position at -8; adding negative moves left to more negative values.

8

Start at $0$ on a number line and add $-4$. Which statement correctly describes the movement and the final position?

Move right 4 units; end at $4$

Do not move; end at $0$

Move left $-4$ units; end at $-4$

Move left 4 units; end at $-4$

Explanation

This question tests interpreting p + q on a number line: start at p = 0, move distance |q| = 4 units in the direction determined by the sign of q = -4 (left if negative), ending at p + q = -4. In number line addition, locate the starting position p = 0, identify the distance to move |-4| = 4 units, determine the direction from the sign of q (negative, so move left toward smaller numbers), and land at 0 + (-4) = -4. For example, 7 + (-4) starts at 7, moves left 4, ends at 3; or -3 + (-6) starts at -3, moves left 6, ends at -9. The correct interpretation is starting at 0, moving left 4 units, and ending at -4, which matches choice C. A common error is wrong direction, like moving right to 4, or treating distance as signed like 'left -4 units' confusingly. The process is: (1) locate p = 0 on the number line, (2) determine |q| = 4 distance, (3) determine direction (negative → left), (4) move left 4 from 0, (5) mark final position at -4. Sign rules: adding negative decreases the value, moving left; mistakes often confuse direction from the sign.

9

On a number line, start at $-3$ and add $-6$. You move a distance of $|-6|$ units in the direction of the sign of $-6$. What is the final position (the value of $-3+(-6)$)?

Start at $-3$, move right 6 units, end at $3$.

Start at $-6$, move left 3 units, end at $-9$.

Start at $-3$, move left 6 units, end at $-9$.

Start at $-3$, do not move, end at $-3$.

Explanation

This question tests interpreting p + q on a number line: start at p=-3, move distance |q|=|-6|=6 units in the direction determined by the sign of q=-6 (right if positive, left if negative), ending at p+q=-9. Number line addition: locate starting position p=-3 (can be positive, negative, or zero), identify distance to move |q|=6 (magnitude of q: |-4|=4 units, |5|=5 units regardless of sign), determine direction from sign of q (if q>0 move right toward larger numbers, if q<0 move left toward smaller), land at p+q=-9. Example: 7+(-4) starts at 7 (p=7), moves left 4 units (q=-4, distance=4, direction=left), ends at 3 (7-4=3, or thinking: 7 is 4 more than 3, moving left 4 from 7 reaches 3); context: temperature -5°C rises 8° (adds +8): start -5, move right 8 units (positive rise), end at 3°C (-5+8=3). The correct interpretation is starting at position -3, moving a distance of 6 units to the left (since -6 is negative), and ending at the final position of -9. A common error is choosing the wrong direction, like moving right for a negative addition (as in choice A, ending at 3), or starting at the wrong position like -6 instead of -3 (choice B), or not moving at all (choice D). The process is: (1) locate p=-3 on the number line (mark starting position), (2) determine |q|=6 distance, (3) determine direction (q negative→left), (4) move from p left 6 units, (5) mark final position at -9 (p+q result). Sign rules: adding positive increases (moves right on number line to larger), adding negative decreases (moves left to smaller); mistakes: direction from sign confused (most common error: thinking negative addition moves right), distance as signed quantity (using -6 as distance when should use 6).

10

On a number line, what does adding $-6$ to $-3$ mean?

Compute $-3+(-6)$ by describing the move and identifying the final position.

Start at $-3$, move left 6 units, end at $-9$

Start at $0$, move left 6 units, end at $-6$

Start at $-3$, move right 6 units, end at $3$

Start at $-6$, move left 3 units, end at $-9$

Explanation

This question tests interpreting p + q on a number line: start at p = -3, move distance |q| = 6 units in the direction determined by the sign of q = -6 (left if negative), ending at p + q = -9. In number line addition, locate the starting position p = -3 (negative, left of zero), identify the distance to move |-6| = 6 units, determine the direction from the sign of q (negative, so move left toward smaller numbers), and land at -3 + (-6) = -9. For example, -3 + (-6) starts at -3, moves left 6 units, ending at -9; or 2 + 5 starts at 2, moves right 5, ends at 7. The correct interpretation is starting at -3, moving left 6 units, and ending at -9, which matches choice B. A common error is wrong direction, like moving right for negative addition, leading to 3, or starting at the wrong position like 0 or -6. The process is: (1) locate p = -3 on the number line, (2) determine |q| = 6 distance, (3) determine direction (negative → left), (4) move left 6 from -3, (5) mark final position at -9. Sign rules: adding negative decreases the value, moving left to more negative; contexts like temperature dropping further reinforce this.

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