Nine-Digits-&-Equal-Products
1. Find this product: 158 × 23 = ________
2. Now write down the four digits that were NOT used in the two
factors above in Step 1. (That means, this time write down
4, 6, 7, and 9.)
3. Use those four digits to make two 2-place numbers in such a
way that when you multiply them, you will get the same product
that you found in Step 1.
CAN YOU DO IT?
Now, try the same kind of thing with these problems.
A) 174 × 32 = _________ and ______ × ______ = __________
B) 532 × 14 = _________ and ______ × ______ = __________
C) 158 × 32 = _________ and ______ × ______ = __________
In the next two problems, use the four left over digits to make
a 3-place number and a one-place number for the other multiplication.
D) 327 × 18 = _________ and ______ × ______ = __________
E) 329 × 14 = _________ and ______ × ______ = __________
In the last two problems, use the five left over digits to make
a 3-place number and a 2-place number for the other multiplication.
F) 96 × 73 = _________ and ______ × ______ = __________
G) 58 × 69 = _________ and ______ × ______ = __________
Source for idea: H. E. Dudeney, Amusements in Mathematics. Dover, 1958.
pp. 14 & 156.
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