What is the divisibility by 2 Rule?. Even numbers are multiples of 2. A number is even if ends in 0,2,4,6, or 8. What is the divisibility by 3 rule?. A number is divisible by 3 if the sum of its digits is divisible by 3. 372, for instance, is divisible by 3 since sum of its digits (3+7+2) is 12. And 12 is divisible by 3. What is the divisibility by 4 rule?. A number is divisible by 4 if the number\'s last two digits are divisible by 4. 9,312, for instance, is divisible by 4 since its last 2 digits are 12. And 12 is divisible by 4. What is the divisibility by 5 rule?. A number is divisible by 5 if its last digit is a 0 or 5. What is the divisibility by 6 rule?. Since 6 is a multiple of 2 and 3, the rules for divisibility by 6 are a combination of the rule for 2 and the rule for 3. Divisibility by 8 Rule. A number passes the test for 8 if the las Read full Tips & Tricks
Faster Percentage Calculation
The quickest way to calculate percentages is to multiply numbers first and handle two decimal places later.
For example, 20% of 70 is 20 x 70 = 1400, so the answer is 14. .
70% of 20 is also 14.
To calculate the percentage of 72 or 29, then round up and down to the nearest multiple (70 and 30 respectively) to get a quick approx result.