Brain Teaser: Change one letter to transform "brain" into "smart" step by step.

Let’s solve this step by step.

We are given a word ladder that starts with brain and ends with smart.
We must change one letter at a time to go from “brain” to “smart”, using the clues on the right to guide each step.

The clues (in order) are:
1. do this to hair → ?
2. every business has → ?
3. tasteless → ?
4. empty → ?
5. opposite of white → ?
6. loose → ?
7. a pile → ?
8. bare → ?
9. begin → ?

And we start with: brain

---

Step 0: Start with brain

Clue 1: “do this to hair” — what do you do to hair? You braid it!
→ Change ‘n’ in brain to ‘d’ → braid

Check: brain → braid ✔ (change last letter)

Clue 2: “every business has” — every business has a brand? Or maybe board? Wait… let’s think.

Actually, “every business has” — could be brand, but let’s see if we can get there from “braid”.

From “braid”, change one letter to match clue 2.

What if we change ‘i’ to ‘u’? → braud? Not a word.

Change ‘a’ to ‘o’? → brold? No.

Wait — maybe “every business has” = board? Like board of directors? But how to get from braid to board?

braid → broad? That’s changing ‘i’ to ‘o’ → broad

Is “broad” related to “every business has”? Not really.

Alternative: “every business has” = profit? Too long.

Wait — perhaps “every business has” = name? Not helpful.

Let’s look ahead. We need to eventually reach “smart”.

Maybe try working backward too? But let’s stick forward.

Another idea: “do this to hair” = brush? But that doesn’t come from brain easily.

Wait — “braid” is correct for clue 1.

Now clue 2: “every business has” — perhaps trade? As in trade or commerce?

Can we go from braid → trade?

braid → braed? No.

braid → bread? Change ‘i’ to ‘e’ → bread

Is “bread” something every business has? In slang, yes — “bread” means money. Maybe acceptable?

But let’s check next clue: “tasteless”

If we have “bread”, then tasteless → bland?

bread → bland? Change ‘r’ to ‘l’ → bland

Yes! And “bland” means tasteless ✔

So far:

brain → braid (clue 1: do this to hair)
braid → bread (clue 2: every business has — slang for money)
bread → bland (clue 3: tasteless)

Clue 4: “empty” — what word means empty? blank?

bland → blank? Change ‘d’ to ‘k’ → blank

Yes! Blank means empty ✔

Clue 5: “opposite of white” — black?

blank → black? Change ‘l’ to ‘c’ → black

Yes! Opposite of white is black ✔

Clue 6: “loose” — slack?

black → slack? Change ‘b’ to ‘s’ → slack

Yes! Slack means loose ✔

Clue 7: “a pile” — stack?

slack → stack? Change ‘l’ to ‘t’ → stack

Yes! A pile is a stack ✔

Clue 8: “bare” — stark?

stack → stark? Change ‘c’ to ‘k’? Wait, stack → stark would require changing two letters? Let’s see:

stack → stak? Not a word.

stack → stalk? Change ‘c’ to ‘k’? Still not helping.

Wait — “bare” synonym: stark? Yes, stark can mean bare or plain.

How to get from stack to stark?

stack → stank? No.

stack → stick? Then stick → stark? Stick → stark changes ‘i’ to ‘a’ and ‘c’ to ‘k’ — two changes.

Not allowed.

Alternative: after “slack”, instead of going to “stack”, go to “slack” → “slake”? Not helpful.

Wait — maybe “a pile” = heap? But heap doesn’t connect well.

Another thought: “loose” = slack, then “a pile” = mound? Too different.

Wait — let’s re-express:

After “black” (clue 5), clue 6 is “loose” → slack ✔

Then clue 7: “a pile” → perhaps stock? Like stockpile?

slack → stock? Change ‘l’ to ‘t’ → stock

Yes! Stock can mean a pile or supply ✔

Then clue 8: “bare” → stork? No.

stock → stok? No.

stock → sock? Then sock → stark? Not direct.

Wait — “bare” synonym: naked, exposed, stark

How about: stock → stork? No.

Another path: from “black” → “blacks”? Plural? Not helpful.

Wait — let’s try:

After “blank” (clue 4), instead of “black”, go to “blanc”? Not English.

Perhaps I made a wrong turn.

Let me list the target words again based on clues:

Start: brain

Clue 1: do this to hair → braid

Clue 2: every business has → ? From braid, what one-letter change gives a word meaning “every business has”?

What about brand? braid → brand? Change ‘i’ to ‘n’ → brand

Yes! Every business has a brand ✔

That’s better than “bread”!

So:

brain → braid (clue 1)
braid → brand (clue 2)

Clue 3: tasteless → bland

brand → bland? Change ‘r’ to ‘l’ → bland ✔

Clue 4: empty → blank

bland → blank? Change ‘d’ to ‘k’ → blank ✔

Clue 5: opposite of white → black

blank → black? Change ‘l’ to ‘c’ → black ✔

Clue 6: loose → slack

black → slack? Change ‘b’ to ‘s’ → slack ✔

Clue 7: a pile → stack

slack → stack? Change ‘l’ to ‘t’ → stack ✔

Clue 8: bare → stark

stack → stark? How?

stack → stak? Not a word.

stack → stick? Then stick → stark? Two changes.

Wait — stack → stank? No.

Alternative: “bare” = barren? Too long.

Or “bare” = nude? Doesn’t fit.

Wait — what if “bare” = stark, and we go from “stack” to “stark” via “stuck”?

stack → stuck? Change ‘a’ to ‘u’ → stuck

Is “stuck” related to “bare”? No.

But clue 8 is “bare”, so we need a word meaning bare.

Another idea: after “slack”, go to “slacks”? Plural pants? Not helpful.

Wait — let’s look at the final word: smart

We need to end at smart.

Current chain:

brain → braid → brand → bland → blank → black → slack → stack → ??? → smart

From stack to smart: stack → stank → sank → sank? No.

stack → stick → sick → slick → slick? Not helping.

Wait — what if after “black”, we go to “blacks” → no.

Alternative path:

After “blank” (clue 4), instead of “black”, go to “blanc” — not valid.

Or “blank” → “bank”? Change ‘l’ to ‘n’ → bank

Is “bank” opposite of white? No.

But “bank” might relate to later clues?

Clue 5 is “opposite of white” — must be black.

So probably black is correct.

Let’s try from “slack” → “slake” → “shake” → “shale” → “shall” → “shall” to “smart”? No.

Wait — here’s an idea:

After “slack” (clue 6: loose), clue 7: “a pile” → heap

slack → slak? No.

slack → shack? Change ‘l’ to ‘h’ → shack

Is “shack” a pile? Kind of — a small building, not really a pile.

But “shack” → “shack” to “shark”? No.

Another thought: “a pile” = mound, but hard to reach.

Let’s consider: from “black” → “blacks” → “backs” → “bakes” → “bakes” to “barks” → “barks” to “barks” — not helping.

Wait — let’s search for common word ladders from brain to smart.

I recall a standard solution:

brain → braid → brand → bland → blank → black → slack → stack → stuck → stunt → shunt → shunt? No.

Wait — here’s a better way:

Let’s list the required intermediate words based on clues:

We have 9 clues, so 9 steps after "brain", ending at "smart".

Positions:

0: brain
1: ? (clue 1)
2: ? (clue 2)
3: ? (clue 3)
4: ? (clue 4)
5: ? (clue 5)
6: ? (clue 6)
7: ? (clue 7)
8: ? (clue 8)
9: ? (clue 9)
10: smart

Wait, the ladder has 10 rungs including start and end? Let's count the boxes.

In the image description, it says "change one letter in each word to complete the word ladder", and shows a ladder with multiple rungs.

Typically, for such puzzles, the number of rungs equals the number of steps + 1.

But let's assume we need 9 intermediate words between brain and smart? That seems too many.

Looking back at the user's text: "DIRECTIONS: Change one letter in each word to complete the word ladder. Use the clues."

And the clues are listed as 9 items.

Also, the ladder visually likely has 10 slots: start, then 8 intermediates, then end? Or 9 intermediates?

To simplify, let's map the clues to positions.

Assume:

Position 0: brain (given)

Position 1: answer to clue 1

Position 2: answer to clue 2

...

Position 9: answer to clue 9

Position 10: smart (given)

So we need 9 words in between.

But that might be overcomplicating.

Perhaps the clues correspond to each rung except the first and last.

Let me try a known solution for "brain" to "smart" word ladder.

Upon recalling, a common solution is:

brain
braid
brand
bland
blank
black
slack
stack
stuck
stunk? No.

Wait:

brain → braid
braid → brand
brand → bland
bland → blank
blank → black
black → slack
slack → stack
stack → stuck
stuck → stump? No.

Another path:

After "stack", go to "stark" directly? Not possible.

Unless we use "stark" for "bare", and find a way.

Let's try:

From "slack" → "slacks" (not helpful)

Or "slack" → "slake" → "quake" → "quack" — no.

Here's a breakthrough:

Clue 8: "bare" — what if it's "stark", and we go from "stack" to "stark" via "stark" is not reachable in one step.

But what if we go from "black" to "blacks" to "backs" to "bakes" to "bakes" to "barks" to "barks" to "barks" — still not.

Wait — let's consider that "loose" might be "limp", but not from black.

Another idea: perhaps "every business has" is "office"? Not from braid.

Let's try a different approach for clue 2.

From "braid", what one-letter change gives a word that fits "every business has"?

"braid" -> "bride"? Not relevant.

"braid" -> "bread" -> as before.

Then "bread" -> "breed"? Not tasteless.

"bread" -> "bead"? No.

Perhaps "tasteless" is "flat", but not from bread.

Let's look online or recall that a standard solution is:

brain
braid
brand
bland
blank
black
slack
stack
stuck
stunt
shunt
shunt to smart? No.

Wait, here's a correct sequence I found in memory:

brain
braid
brand
bland
blank
black
slack
stack
stark
start
smart

Let's verify:

- brain to braid: change n to d — do this to hair ✔
- braid to brand: change i to n — every business has a brand ✔
- brand to bland: change r to l — tasteless ✔
- bland to blank: change d to k — empty ✔
- blank to black: change l to c — opposite of white ✔
- black to slack: change b to s — loose ✔
- slack to stack: change l to t — a pile ✔
- stack to stark: change c to k? Stack to stark is not one letter; stack is s-t-a-c-k, stark is s-t-a-r-k — so change c to r? But that's position 4, and k is position 5.

Stack: s-t-a-c-k
Stark: s-t-a-r-k

So change 'c' to 'r' — yes! One letter change: position 4 from c to r.

And "stark" means bare or plain ✔

Then clue 9: "begin" — what word means begin? start

stark to start: change k to t — s-t-a-r-k to s-t-a-r-t — change last letter k to t → start

And "start" means begin ✔

Then start to smart: change t to m — s-t-a-r-t to s-m-a-r-t — change second letter t to m → smart

Perfect!

So the full ladder is:

1. brain
2. braid (clue 1: do this to hair)
3. brand (clue 2: every business has)
4. bland (clue 3: tasteless)
5. blank (clue 4: empty)
6. black (clue 5: opposite of white)
7. slack (clue 6: loose)
8. stack (clue 7: a pile)
9. stark (clue 8: bare)
10. start (clue 9: begin)
11. smart

But the ladder in the worksheet likely has 10 rungs including start and end, so perhaps the clues are for the 9 steps in between.

In any case, the words to fill in the ladder (excluding start and end) are:

braid, brand, bland, blank, black, slack, stack, stark, start

And they match all clues.

Now, to confirm the transitions:

- brain → braid: change 'n' to 'd'
- braid → brand: change 'i' to 'n'
- brand → bland: change 'r' to 'l'
- bland → blank: change 'd' to 'k'
- blank → black: change 'l' to 'c'
- black → slack: change 'b' to 's'
- slack → stack: change 'l' to 't'
- stack → stark: change 'c' to 'r'
- stark → start: change 'k' to 't'
- start → smart: change 't' to 'm'

All are single letter changes.

And all clues are satisfied.

Final Answer: The completed word ladder is:

brain
braid
brand
bland
blank
black
slack
stack
stark
start
smart