4. The following numbers are divisible by 15. Givethe possible values

1.	4. The following numbers are divisible by 15. Givethe possible values of a, b , c in the numbers(1) 24b5 (2 ) 9a80 (3 ) 78b5 Please explain step by step
Answer» if any number is divided by 3 and 5 then the number is also DIVISIBLE by 15 now, the DIVISIBILITY rule of 3 is if the sum of all the digits are divisibel by 3 then the number is also divisible by 3 the divisibility rule of 5 is if the last digit is 0 or 5 in1)the sum of all digit=(2+4+5+b) =11+b therefore, the nearest number to 11 divisible by 3 is 12 therefore, b=12-11 =1 since, the last digit is 5 theregore it the number is also divisible by 5 2)sum of digit=(9+a+8+0)=17+a therefore a=18-17=1 since , the last digit is 0 then it is divisible by 5 3)sum of digit=(7+8+5+b)=20+b therefore, b=21-20=1 since, the last digit is 5 therefore, the number is divisible by 5

4. The following numbers are divisible by 15. Givethe possible values of a, b , c in the numbers(1) 24b5 (2 ) 9a80 (3 ) 78b5 Please explain step by step

Answer»

if any number is divided by 3 and 5 then the number is also DIVISIBLE by 15

now, the DIVISIBILITY rule of 3 is if the sum of all the digits are divisibel by 3 then the number is also divisible by 3

the divisibility rule of 5 is if the last digit is 0 or 5

in1)the sum of all digit=(2+4+5+b)

=11+b

therefore, the nearest number to 11 divisible by 3 is 12

therefore, b=12-11

since, the last digit is 5 theregore it the number is also divisible by 5

2)sum of digit=(9+a+8+0)=17+a

therefore a=18-17=1

since , the last digit is 0 then it is divisible by 5

3)sum of digit=(7+8+5+b)=20+b

therefore, b=21-20=1

since, the last digit is 5

therefore, the number is divisible by 5