Divisibility test of 7
A
number is divisible by 7 if the following is true:
1.
Multiply the ones digit by 2.
2.
Subtract this value from the rest of the number.
3.
Continue this pattern until you find a number you know is or is not divisible
by 7.
Example 7203 is
divisible by 7 because
a)
3 x 2 = 6.
b)
720 – 6 = 714
c) 4 x 2 =8
d) 71 -8 =63 which is divisible by 7.
Hence 7203 is divisible by 7
c) 4 x 2 =8
d) 71 -8 =63 which is divisible by 7.
Hence 7203 is divisible by 7
Example 14443 is not
divisible by 7 because
a)
3 x 2 = 6.
b)
1444 – 6 = 1438 .
c)
8 x 2 = 16.
d) 143 – 16 = 127
e) 7 x 2 = 14
f) 12 - 14 = -2 which is not divisible by 7.
Hence 14443 is not divisible by 7
d) 143 – 16 = 127
e) 7 x 2 = 14
f) 12 - 14 = -2 which is not divisible by 7.
Hence 14443 is not divisible by 7