NUMERICAL ABILITY

Number System:

Test of divisibility:

1. A number is divisible by ‘2’ if it ends in zero or in a digit which is a multiple of

‘2’i.e. 2,4, 6, 8.

2. A number is divisible by ‘3’, if the sum of the digits is divisible by ‘3’.

3. A number is divisible by ‘4’ if the number formed by the last two digits, i.e. tens

and units are divisible by 4.

4. A number is divisible by ‘5’ if it ends in zero or 5

5. A number is divisible by ‘6’ if it divisible by ‘2’ as well as by ‘3’.

6. A number is divisible by ‘8’ if the number formed by the last three digits, i.e,

hundreds tens and units is divisible by ‘8’.

7. A number is divisible by ‘9’ if the sum of its digit is divisible by ‘9’

8. A number is divisible by ‘10’ if it ends in zero.

9. A number is divisible by ‘11’ if the difference between the sums of the digits in

the even and odd places is zero or a multiple of ‘11’.

LCM:

LCM of a given set of numbers is the least number which is exactly divisible
by every number of the given set.

HCF:
HCF of a given set of numbers is the highest number which divides exactly
every number of the given set.