Question

If 43751x is divisible by both 5and 10,what is the value of digit x?​

Answer 1

we have 45=5\times945=5×9 also 5 and 9 are co-prime.

now, 25110 is divisible by 5 because its units digit is 0.

again sum of digit =2+5+1+1+0=9=2+5+1+1+0=9

since the sum of digits is divisible by 9, so 25110 is also divisible by 9.

also, since the number is divisible by both 5 and 9, where 5 and 9 are co-prime.

25110 is divisible by their product also i.e 5\times9=455×9=45