Patterns
in numbers
Cast
out nines from a given number to check if it is a multiple of nine.
EXAMPLE
Is 46908 multiple of 9?
46908 = 4 + 6 + 0 + 8
= 18
= 1 + 8
= 9
Let us Know
Any number or combination
of digits in that number which add to 9 can be cast out from the given number. Then
the sum of remaining digits of the number is divisible by 9 or multiple of 9.
In addition problem, we can check the sum by
casting out nines.
EXAMPLE 1
Check the following numbers
whether it is a multiple of 9 or not
24689 = 2 + 4 + 6 + 8 = 20 (It's
not a multiple of 9.)
9108 = 0 (It's a multiple of 9.)
3165 = 1 + 5 = 6 (It's not a
multiple of 9.)
EXAMPLE 2
Check the addition fact
3356 + 4729 = 8085
8 + 4 = 21
12 = 21
1 + 2 = 2 + 1
3 = 3
In subtraction problem, we can check the difference
by casting out nines method.
(Remember that subtraction is nothing more than
addition in reverse).
EXAMPLE
4897 − 2186 = 2711
4897 − 2186 = 2711
19 − 8 = 2
10 − 8 = 2
2 = 2
Let us Know
Think of a two
digit number say 52, then subtract the reverse of its digits, 25 from 52.
Difference = 52 −
25 = 27
27 is a multiple of
9.
Activity
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.