Question

Test the divisibility of 821580 for 4,6,9and11

Answer 1

it is divisible by 4 as last 2 digit are divisible by 4
it is divisible by 6 as it is divisible by 2 and 3
divisible by 9
and
not divisible by 11

Answer 2

To test the divisibility of 821580 for 4 we have to see whether the last two digits are divisible by 4 or not.
Since the last two digits i.e. 80 is divisible by 4, therefore, 821580 is divisible by 4.

For 6 we have to see whether the number is divisible by 2 and 3 or not.
For the number to be divisible by 2 the last digit should be an even number and for the number to be divisible by 3 the sum of the digits in the number should be divisible by 3.
Since the last digit of the number is even so it is divisible by 2 and since the sum of the digits (8+2+1+5+8+0+=24) which is divisible by 3 therefore the number is divisible by 6.

For divisibility of a number with 9 also we have to see whether their sum is divisible by 9 or not . Since their sum i.e. 24 is not divisible by 9 therefore the number is not divisible by 9.

For 11 we have to sum up the digits alternatively from left to right i.e.
821580
0+5+2=7 and 8+1+8=17
Now find the difference ,
17-7=10 which is not divisible by 11. Thus the number is not divisible by 11


Hope it helps you.