| Front | A number is divisible by 3 when... |
| Back | The sum of its digits is a multiple of 3 (Ex: 243 --> 2+4+3 = 9) |
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| Front | A number is divisible by 7 when... |
| Back | Multiplying the units digit by 2 and subtracting it from the number formed by the other digits results in a multiple of 7 or 0 (Ex: 896 --> 89 - 12 = 77; 63 --> 6 - 6 = 0) |
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| Front | A number is divisible by 5 when... |
| Back | Ends in 0 or 5 (Ex: 15, 45, 555, 69.235) |
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