Hops on the line
A positive addend hops right, a negative addend hops left, by its size.
Why it works
Walk forward for gains, backward for losses.
Integers · Add integers · 4.4
Add on the line.
Adding is hopping on the number line: start at the first number, then move right for a positive and left for a negative. Where you land is the sum.
See it work.
On the number line
Start at -2, hop right 6.
-2 + 6 = 4
Watch the method
Add on the line
−2 + 6: start at −2, hop 6 right → 4.
1
Different signs — subtract
Subtract the smaller size from the larger: 6 − 2.
2
Take the bigger sign
6 is the larger size and it is positive, so the answer is positive.
Practice until it feels automatic.
Your turn
Work it out.
Type a whole number — negatives allowed, e.g. -7.
streak 0
best 0
… =
The idea underneath.
From easy to tricky.
Add 1 + -6
1
Different signs — subtract
Subtract the smaller size from the larger: 6 − 1. 6 - 1 = 5
2
Take the bigger sign
6 is the larger size and it is negative, so the answer is negative. 1 + (-6) = -5
Add -5 + 7
1
Different signs — subtract
Subtract the smaller size from the larger: 7 − 5. 7 - 5 = 2
2
Take the bigger sign
7 is the larger size and it is positive, so the answer is positive. -5 + 7 = 2
Add 12 + -9
1
Different signs — subtract
Subtract the smaller size from the larger: 12 − 9. 12 - 9 = 3
2
Take the bigger sign
12 is the larger size and it is positive, so the answer is positive. 12 + (-9) = 3
Where students slip.
Trap
Hopping the wrong direction.
Fix
+ goes right, − goes left.
Trap
Starting from 0 instead of the first number.
Fix
Start at the first addend.
Test yourself.
The Test
12 problems across three tiers. Auto-graded on submit. Hints and a full walkthrough on every question. Your work is saved on this device — sign in to keep it across devices.
0/12Answered
How to answerType just the value. Formatting won't trip you up — we ignore spaces, capital letters, commas, and subscript style, so
t₁ = 5, d = 3 and t1=5,d=3 both count. For a list of numbers, separate them with commas (e.g. 3, 10, 17).Core
Core (4)
C1
Add 1 + -6
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
C2
Add -4 + 10
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
C3
Add -4 + 9
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
C4
Add -7 + 9
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
Apply
Apply (4)
A1
Add -5 + 7
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
A2
Add -8 + 12
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
A3
Add -10 + 8
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
A4
Add 12 + -2
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
Extension
Extension (4)
E1
Add 12 + -9
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
E2
Add 9 + -5
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
E3
Add 9 + -2
Need a hint?
- Start at the first number.
- Hop right for +, left for −.
E4
Add -4 + 5
Need a hint?
- Start at the first number.
- Hop right for +, left for −.