Crypt Arithmetic Problems That Are Simple to Explain

Crypt Arithmetic Problems That Are Simple to Explain


Students in 5th grade math challenge at Seward.
Please perform both checks and write on paper.
Write your name and your E2 teacher's name on
the paper and hand in to Karen Utter on Monday
Nov 5 or Wed Nov 7.

2012 6th Grade Math Challenge Problem #1
162
+XD
-----
2D7

D must equal 5 so we have:

162
+X5
-----
257

When we add X to 6, we must get 5 and a carry of 1.
So, 6 + X = 15, or X = 9

162
+95
-----
257

Check: Do the above with a calculator and verify that it is correct.



2012 6th Grade Math Challenge Problem #5

ON + ON + ON + ON = GO

Adding ON 4 times is the same as multiplying by 4.

ON
x4
-----
GO

Try various values for N.

N can't be zero because then, N and O would be the same.

If N is 1, O = 4 and 4 x O would be 16, generating a carry
and giving a three-digit answer.

If N is 2, O = 8 and 4 x O would be 32, again generating a
carry and giving a three-digit answer.

If N is 3, 4 x 3 = 12. That makes O = 2 with a carry of 1.
G = 4 x 2 + 1, or 9.

This gives:

23
x4
----
92

Check: 23 + 23 + 23 + 23 = 92

Verify this with a calculator.