Explain the divisibility rule of 7.

Divisibility rule for 7:

• First double the last digit of the number.

• Then subtract it from the remaining number.

• If the result is divisible by 7, then the original number will also be divisible by 7. For example: Let’s check if 623 is divisible by 7 or not.

• First double the last digit of the number (3 x 2 = 6).

• Then subtract it from the remaining number (62 – 6 = 56).

• We know that 56 is divisible by 7ie, $\frac{56}{7} \ =8$, then the original number (623) will also be divisible by 7 ie, $\frac{623}{7} \ =89$.