1. Check whether 7112 is divisible by 28 or not?Solution:Divisibility rule of 28 :
If number is divisible by 4 and 7, then number is also divisible by 28.
Divisibility rule of 4 :
The last two digit is divisible by 4, then number is also divisible by 4.
Last 2 digit of 7112 is 12, which is divisible by 4.
`:.` 7112 is divisible by 4.
Divisibility rule of 7 :
2 times the last digit and subtract it from the rest of the number.
If the answer is divisible by 7, then number is also divisible by 7.
(Apply this rule to the answer again if necessary)
`711color{red}{2}=>711 - color{red}{2} xx 2 = 711 -4 = 707`
`70color{red}{7}=>70 - color{red}{7} xx 2 = 70 -14 = 56`
Here 56 is divisible by 7.
`:.` 7112 is divisible by 7.
7112 is divisible by 4 and 7.
`:.` 7112 is divisible by 28.
2. Check whether 9268 is divisible by 28 or not?Solution:Divisibility rule of 28 :
If number is divisible by 4 and 7, then number is also divisible by 28.
Divisibility rule of 4 :
The last two digit is divisible by 4, then number is also divisible by 4.
Last 2 digit of 9268 is 68, which is divisible by 4.
`:.` 9268 is divisible by 4.
Divisibility rule of 7 :
2 times the last digit and subtract it from the rest of the number.
If the answer is divisible by 7, then number is also divisible by 7.
(Apply this rule to the answer again if necessary)
`926color{red}{8}=>926 - color{red}{8} xx 2 = 926 -16 = 910`
`91color{red}{0}=>91 - color{red}{0} xx 2 = 91 = 91`
Here 91 is divisible by 7.
`:.` 9268 is divisible by 7.
9268 is divisible by 4 and 7.
`:.` 9268 is divisible by 28.
3. Check whether 10780 is divisible by 28 or not?Solution:Divisibility rule of 28 :
If number is divisible by 4 and 7, then number is also divisible by 28.
Divisibility rule of 4 :
The last two digit is divisible by 4, then number is also divisible by 4.
Last 2 digit of 10780 is 80, which is divisible by 4.
`:.` 10780 is divisible by 4.
Divisibility rule of 7 :
2 times the last digit and subtract it from the rest of the number.
If the answer is divisible by 7, then number is also divisible by 7.
(Apply this rule to the answer again if necessary)
`1078color{red}{0}=>1078 - color{red}{0} xx 2 = 1078 = 1078`
`107color{red}{8}=>107 - color{red}{8} xx 2 = 107 -16 = 91`
Here 91 is divisible by 7.
`:.` 10780 is divisible by 7.
10780 is divisible by 4 and 7.
`:.` 10780 is divisible by 28.
4. Check whether 7498 is divisible by 28 or not?Solution:Divisibility rule of 28 :
If number is divisible by 4 and 7, then number is also divisible by 28.
Divisibility rule of 4 :
The last two digit is divisible by 4, then number is also divisible by 4.
Last 2 digit of 7498 is 98, which is not divisible by 4.
`:.` 7498 is not divisible by 4.
Hence 7498 is also not divisible by 28.
5. Check whether 9515 is divisible by 28 or not?Solution:Divisibility rule of 28 :
If number is divisible by 4 and 7, then number is also divisible by 28.
Divisibility rule of 4 :
The last two digit is divisible by 4, then number is also divisible by 4.
Last 2 digit of 9515 is 15, which is not divisible by 4.
`:.` 9515 is not divisible by 4.
Hence 9515 is also not divisible by 28.
6. Check whether 10894 is divisible by 28 or not?Solution:Divisibility rule of 28 :
If number is divisible by 4 and 7, then number is also divisible by 28.
Divisibility rule of 4 :
The last two digit is divisible by 4, then number is also divisible by 4.
Last 2 digit of 10894 is 94, which is not divisible by 4.
`:.` 10894 is not divisible by 4.
Hence 10894 is also not divisible by 28.
This material is intended as a summary. Use your textbook for detail explanation.
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