Alexander Bass

Send More Money Puzzle

ADDITION is an imposition,

SEND+MOREMONEY

SUBTRACTION is as bad,

EIGHTFIVEFOUR

MULTIPLICATION is a vexation,

TWO×TWOTHREE

In each puzzle every letter represents a different digit, but a letter does not necessarily stand for the same digit in the case of very puzzle. Additionally, note that the leading digits are not zero.


These puzzles were created by Henry E. Dudeney in 19241. This page has solutions for each.

Addition is an imposition

Given that the sum has one more digit than the summands, it’s reasonable that M must be 1 as the result of a carry.

Notate possible carries as cn :

1c3c2c1SEND+1ORE1ONEY

(Do not confuse the letter O with 0 )

Given that the leading digit was the result of a carry, we can be sure that:

S+1+c3=O+10

Which gives a few branches to follow:

If S =9 and c3=1 , then 11=O +10 and O =1 , which contradicts M =1 making this branch invalid.

Next, if S =8 and c3=1 then 10=O +10 and O =0 . Following this to the next pair of digits being added, we see:

E+c2=N+10

So it must be that c2=1 , which would make E =9 and N =0 which contradicts O =0 making this branch invalid.

Exhausting other options, we are sure that S =9 , O =0 and c3=0

10c2c19END+10RE10NEY

Following this to the next pair of digits being added, we see:

E+c2=N

Given that E N it must be that c2=1 . So:

E+1=N

Following to the next pair of digits be added, we see:

N+R +c1=E+10

Solving with the previous equation, we see that

E+1+R+c1=E+10R+c1=9

Given that S =9 (and therefor R9 ) we know c1=1 and R =8

10119END+108E10NEY

Looking at the final pair of digits, the following is true:

D+E=Y+10

We can carve away at the bounds of by using the values of the known variables we know:

N=E+13N72E62D712(D+E),(Y+10)17

Any combination where D,E <5 is naturally invalid as the sum is less than 12 . Constrain bounds:

5E65D7

Enumerate possibilities

5+5=10(1)5+6=11(2)6+5=11(3)7+5=12(4)6+6=12(5)7+6=13(6)

Of theses (1) and (5) are invalid as D =E . Furthermore (3) and (6) are invalid because E+1=D=N . Finally (2) and (3) are invalid because the sum is out of bounds. This leaves:

7+5=12

Thus D =7, E =5, Y =2, N=6

10119567+108510652

Subtraction is as bad

EIGHTFIVEFOUR

Compared with the other two, I consider this problem lousy. The other problems have just one solution, whereas this one has twenty. With how many solutions exist, I’d say the best manual strategy is to guess and check. Instead, I wrote a python program2 to find all solutions.

View Code
def digits(n):
    dig = []
    while n > 0:
        dig.append(n % 10)
        n //= 10
    return list(reversed(dig))

for a in range(10000, 99999):
    for b in range(1000, 9999):
        if not (1000 <= a-b <= 9999):
            continue
        [E, I, G, H, T] = digits(a)
        [F, I_2, V, E_2] = digits(b)
        [F_2, O, U, R] = digits(a-b)
        if I != I_2 or E != E_2 or F != F_2:
            continue
        unique = [E, I, G, H, T, F, V, O, U, R]
        if len(set(unique)) != len(unique):
            continue
        print(a, b)
View all solutions
12348 - 6251 = 6097
12348 - 6291 = 6057
12375 - 6281 = 6094
12375 - 6291 = 6084
12780 - 6231 = 6549
12780 - 6241 = 6539
14820 - 7451 = 7369
14820 - 7461 = 7359
15230 - 7541 = 7689
15230 - 7581 = 7649
16725 - 8631 = 8094
16725 - 8691 = 8034
16743 - 8651 = 8092
16743 - 8691 = 8052
16905 - 8631 = 8274
16905 - 8671 = 8234
17036 - 8741 = 8295
17036 - 8791 = 8245
17054 - 8761 = 8293
17054 - 8791 = 8263

Multiplication is a vexation

TWO×TWOTHREE

For convenience:

TWO=aTHREE=bb=a2

First, note that the result has exactly five digits. The largest 5-digit square is 3162=99856 and the smallest is 1002=10000 Notate constraints

100a316

We can further constrain the bounds by noticing that the first digits of a,b are shared as T .

10000=10019999141.420000141.429999173.230000173.239999199.9

The first-digit constraint can only be true when T=1 and a141

Now, notice how the digit E is determined only by the value of the square of O .

O2=E+10q1

Find squares of digits

Digit0123456789Square0149656941

Meaning E must be one of those square digits

Let’s now focus on the last two digits, EE which are determined only by the value of (O+10W)2 . Expand:

O2+20OW+100W2=EE+100q2

We can ignore the 100s term as we’re only focusing on the last two digits.

O2+20OW=EE+100q3

Now, we’ve already determined that O and E are constrained to certain values. Try each possibility

OEE000111244399466555666799844

Possibilities where O and E share digits are naturally invalid and can be removed.

OEE244399466799844

We use these possibilities in the equation found above to determine W

O2+20OW=EE+100q3

Try O =2, EE =44 :

4+40W=44+100q340W=40+100q32W=2+5q3

This equation has solutions at W=1,6 . We can ignore W=1 as we have already determined T=1 . Looking at W=6 we see a=162 which is out of bounds; a141 .

As all branches are dead ends, we are sure that O2

Instead, try O=3, EE=99 :

9+60W=99+100q460W=90+100q46W=9+10q4

Which has no solutions. Dead end. O3

Instead, try O =4 EE=66 :

16+80W=66+100q580W=50+100q58W=5+10q5

Which has no solutions. Dead end. O4

Instead, try O =7 EE=99 :

49+140W=99+100q6140W=50+100q614W=5+10q6

Which has no solutions. Dead end. O 7

Therefor, by elimination O =8

64+160W=44+100q7160W+20=100q78W+1=5q7

Which has one valid solution, W=3 . Substitute in known digits

138×1381HR44

Naturally, the remaining digits are found within 1382=19044

138×13819044


Further reading

  1. The Strand Magazine, July 1924 edition. Page 97. Henry E. Dudeney (view online).
    Note that a fourth puzzle on division is found in the original source. I have excluded this puzzle as I couldn’t properly typeset it. ↩︎

  2. It’s very inefficient. I know. ↩︎