Celebrating Chika Ofili

It has happened again!
12 year old Nigerian boy based in the UK ,Chika Ofili has been presented with a special recognition award for making a new discovery in mathematics.

Chika Test
To test for divisibility by 7.
Multiply the last digit by 5 and add it to the remaining number. Here we go!
For example take the number 532
53+2 x 5=53+10= 63
63 is a multiple of 7, so 532 is a multiple of 7 and therefore divisible by 7.
Another one, take 987
98+7 x 5= 98 +35 = 135
13+ 3 x 5 = 13 +15
                = 28
then 28 is divisible by 7, so 987 is divisible by 7.
Even the test can verify big numbers no matter how big they are,

For example-
8955795758
895579575+8 x 5 =895579575+ 40 = 895579615
89557961 +5 x 5 = 89557961 + 25 = 89557986
8955798 + 5 x 6 =8955798 + 30= 8955828
895582 + 5 x 8 =895582 + 40 = 895622
89562+ 5 x 2=89562+10 =89572
8957 + 5 x 2 =8957 +10 =8967
896 + 5 x 7 =896 +35 = 931
93 + 5 x 1 =93 + 5 =98
9 + 5 x 8 = 9 +40 =49
Since 49 is a multiple of 7, so 8955795758 is a multiple of 7 and therefore divisible by 7.
Wao!!