Powers of two are halvings
÷2 is one halving, ÷4 is two, ÷8 is three. For ÷5, flip it around: ÷5 = ×2 ÷ 10, because 5 is half of 10. So 85 ÷ 5 = 170 ÷ 10 = 17.
Why it works
Folding in half repeatedly gets you to ÷4 and ÷8 fast.
Mental Math · Division · D2
Divide by halving.
Dividing by 2, 4, and 8 is just halving — once, twice, or three times. And dividing by 5 is the mirror of multiplying: double the number and divide by 10.
How to think about it.
Watch the method
Divide by halving
96 ÷ 4 means halve twice: 96 → 48 → 24. Dividing by 4 is halving and halving again; ÷8 is three halvings.
= ?
1
Halve it…
2
…and halve again.
Practice until it feels easy.
Your turn
Solve it in your head.
Use the method, then check. Stuck? Reveal the steps.
streak 0
best 0
… =
The idea underneath.
From easy to tricky.
48 ÷ 4
1
Halve
48 → 24.
2
Halve again
24 → 12.
96 ÷ 8
1
Halve
96 → 48.
2
Again
48 → 24.
3
Again
24 → 12.
85 ÷ 5
1
Double
85 × 2 = 170.
2
÷10
170 ÷ 10 = 17.
Where students slip.
Trap
Halving the wrong number of times for ÷4 or ÷8.
Fix
÷4 = halve twice. ÷8 = halve three times. Count the halvings.
Trap
For ÷5, dividing by 10 then doubling (reversed).
Fix
÷5 = ×2 then ÷10. Double first, then drop a zero: 85 → 170 → 17.
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
48 ÷ 2 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
C2
96 ÷ 4 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
C3
88 ÷ 8 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
C4
72 ÷ 4 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
Apply
Apply (4)
A1
124 ÷ 4 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
A2
96 ÷ 8 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
A3
156 ÷ 4 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
A4
184 ÷ 8 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
Extension
Extension (4)
E1
85 ÷ 5 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
E2
240 ÷ 5 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
E3
130 ÷ 5 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.
E4
96 ÷ 2 = ?
Need a hint?
- ÷2 is halving; ÷4 is halve twice; ÷8 is halve three times.
- Dividing by 5? Double the number, then divide by 10.