Flashcards in Number Properties: Divisibility Deck (11)

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1

## Divisible by 2

### Units digit is even: {0, 2, 4, 6, 8}.

2

## Divisible by 9

### Sum of digits is divisible by 9.

3

## Divisible by 3

### Sum of digits is divisible by 3.

4

## Divisible by 4

### 2-digit number at the end is divisible by 4. Alternatively, X is a number made up of digits a...bc. If the last 2 digits of the number, bc, mod 4 = 0, then X is divisible by 4. If b is odd, then X is divisible by 4 if c is 2 or 6. If b is even, then X is divisible by 4 if c is 0, 4, or 8.

5

## Divisible by 10

### Units digit is zero (0).

6

## Divisible by 6

### The number is divisible by 2 (even) and by 3.

7

## Divisible by 5

### Units digit is zero (0) or 5.

8

## Divisible by 7

### X is a number made up of digits a...bc. If (a...b - 2*c) mod 7 = 0 then X is divisible by 7. This process can be applied recursively.

9

## Divisible by 8

### X is a number made up of digits a...bcd. If the last 3 digits of the number, bcd, mod 8 = 0, then X is divisible by 8. If b is even then, X is divisible by 8 if cd mod 8 = 0. If b is odd then, X is divisible by 8 if (cd - 4) mod 8 = 0.

10

## Divisible by 11

### Alternating difference/sum is divisible by 11. Alternatively, X is a number made up of digits abcd. If (((a - b) + c) - d) mod 11 = 0, then X is divisible by 11.

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