a number is divisible by
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If...........
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Example:
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2
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the last number is even (0;2;4;6;8)
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128 is divisible by 2
129 is not
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3
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the sum of the digits is divisible by 3
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381 (3+8+1=12 and 12÷3=4) YES!
217 (2+1+7=10 and 10÷3=31/3) NO!
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4
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the last two digits are divisible by 4
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1312 (12 ÷ 4 = 3)is divisible
7019 is not
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5
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the last digit is 0 or 5
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175 is divisible
809 is not
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6
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The number is divisible by both 2 and 3 using the rule above
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114 (it is even, and 1+1+4=6 and 6 ÷ 3 =2 yes!)
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7
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Double the last digit and subtract it from a number made by the other digits. The result must be 0 or divisible by 7. (We can apply this rule to that answer again)
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- 672 (Double 2 is 4, 67-4=63, and 63÷7=9) Yes
- 905 (Double 5 is 10, 90-10=80, and 80÷7=11 3/7) No
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8
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The last three digits are divisible by 8
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- 109816 (816÷8=102) Yes
- 216302 (302÷8=37 3/4) No
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9
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The sum of the digits is divisible by 9
(Note: This rule can be repeated when needed)
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- 1629 (1+6+2+9=18, and again, 1+8=9) Yes
- 2013 (2+0+1+3=6) No
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10
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the number ends in 0
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220 YES!
221 NO!
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