Divisibility Rule For 20 With Examples

Divisibility Rule For 20

The divisibility rule for 20 is straightforward because it combines the rules for 4 and 5, since (20 = 4 x 5). For a number to be divisible by 20, it must satisfy both of these conditions.

Divisibility Rules for 4 and 5:

1. Divisibility by 4:

• A number is divisible by 4 if the last two digits of the number form a number that is divisible by 4.

1. Divisibility by 5:

• A number is divisible by 5 if its last digit is either 0 or 5.

Combining the Rules for 20:

For a number to be divisible by 20, it must:

• Have its last digit as 0 (to satisfy divisibility by 5).
• The last two digits must form a number that is divisible by 4.

Examples:

1. Example: 160

• Last digit: 0 (satisfies the rule for 5).
• Last two digits: 60. Check if 60 is divisible by 4:
  • (60/4 = 15) (which is an integer).
• Both conditions are satisfied, so 160 is divisible by 20.

1. Example: 240

• Last digit: 0 (satisfies the rule for 5).
• Last two digits: 40. Check if 40 is divisible by 4:
  • (40/4 = 10) (which is an integer).
• Both conditions are satisfied, so 240 is divisible by 20.

1. Example: 85

• Last digit: 5 (satisfies the rule for 5).
• Last two digits: 85. Check if 85 is divisible by 4:
  • (85/4 = 21.25) (not an integer).
• 85 is not divisible by 20.

1. Example: 80

• Last digit: 0 (satisfies the rule for 5).
• Last two digits: 80. Check if 80 is divisible by 4:
  • (80/4 = 20) (which is an integer).
• Both conditions are satisfied, so 80 is divisible by 20.

1. Example: 45

• Last digit: 5 (satisfies the rule for 5).
• Last two digits: 45. Check if 45 is divisible by 4:
  • (45/4 = 11.25) (not an integer).
• 45 is not divisible by 20.

Summary

To determine if a number is divisible by 20, check that:

• The last digit is 0 (for divisibility by 5).
• The last two digits form a number that is divisible by 4.

By applying these rules, we can quickly assess whether a number is divisible by 20.