Different methods for multiplication
1. Vertical Method (Normal way)
2. Doubling & Halving Method (by finding equivalent multiplication)
Example: 15 x 16 = 30 x 8 = 240
so, 15 x 16 is equivalent to 30 x 8
Note: Always DOUBLE the ODD NUMBER and HALVE the EVEN NUMBER
3. Partitioning Method
Example: 235 x 6 = (200 x 6) + (30 x 6) + (5 x 6) = 1200 + 180 + 30 = 1410
Divisibility by
Rule
Example
2
The number must be even
24
129
1 + 2 + 9 = 12
3
Add all the digits and see if the
number can be divided by 3
724
4
The last two digits must be
divisible by 4
60, 35
5
The number must end with 0 or
5
The number must end with 0
90
The number must end with
these digits:
00 or 25 or 50 or 75
500, 525, 550, 575
10
25