If subtracting twice of last digit from the number formed by remaining digits is divisible by 7,
Then number is divisible by 7
Is 371 divisible by 7?
Twice of last digit = 2 × 1 = 2
Remaining digits = 37
Subtraction = 37 – 2 = 35
Since 35 is divisible by 7
∴ 371 is divisible by 7
Is 434 divisible by 7?
Twice of last digit = 2 × 4 = 8
Remaining digits = 43
Subtraction = 43 – 8 = 35
Since 35 is divisible by 7
∴ 434 is divisible by 7
Is 672 divisible by 7?
Twice of last digit = 2 × 2 = 4
Remaining digits = 67
Subtraction = 67 – 4 = 63
Since 63 is divisible by 7
∴ 672 is divisible by 7
Is 105 divisible by 7?
Twice of last digit = 2 × 5 = 10
Remaining digits = 10
Subtraction = 10 – 10 = 0
Since 0 is divisible by 7
∴ 105 is divisible by 7
Is 905 divisible by 7?
Twice of last digit = 2 × 5 = 10
Remaining digits = 90
Subtraction = 90 – 10 = 80
Since 80 is not divisible by 7
∴ 905 is not divisible by 7
