## Code Cracking

Mathematics, Algebra and Function

### Objective

Students use codes to learn pre-algebra concepts.

### Directions

Facts and Reminders
Simple Codes
This is a simple code because 43 + 32 = 75.

 43 + 32 A = 7 C = 5 AC

Using Reverse Operations
In the problem below, to crack the code you must subtract 98 from 123. The answer is 25.
 Problem Step Check Solution 98 98 + DF 123 - 98 = 25 + 25 D = 2 F = 5 123 123

In this next problem, to crack the code, you must divide 1,428 by 42. The answer is 34.
 Problem Step Check Solution 42 42 x AF x 34 168 1428 ÷ 42 = 34 168 A = 3 F = 4 1260 1260 1428 1428

Using Number Sense
In the problem below, you can try two ways to crack the code. One way is to try each digit 1 through 9. Another way is knowing that 6 = 2 x 3 and trying 2 first.
 Problem Check Solution 31 31 x AA x 22 6A 62 A = 2 6A0 620 68A 682

In the next problem, you know that the only number that added to itself and equals 2 is 1.
 Problem Check Solution BBB 111 + BBB + 111 B = 1 2 2 2 222

In the problem below, ask yourself the question, "Which number times itself equals 9?" The answer is 3.
 Problem Check Solution FFF 333 x F x 3 F = 3 999 999

### Resources

• Code Cracking activity sheet
• pencils