Question

EXERCISE 16.2
1. If 21y5 is a multiple of 9, where y is a digit, what is the value of y?
2. If 3125 is a multiple of 9, where z is a digit, what is the value of z?
You will find that there are two answers for the last problem. Why is this so?
3. If 24x is a multiple of 3, where x is a digit, what is the value of x?
(Since 24x is a multiple of 3, its sum of digits 6+ x is a multiple of 3; so 6 + x is one
of these numbers: 0,3,6,9,12,15,18,.... But since x is a digit, it can only be that
6+x=6 or 9 or 12 or 15. Therefore, x = 0 or 3 or 6 or 9. Thus, x can have any of
four different values.)
4. If 3125 is a multiple of 3, where z is a digit, what might be the values of z?
WHAT HAVE WE DISCUSSED?
can be written in general form. Thus, a two digit number ab will be written as
b.​

Answer 1

1. y= 1

2.not proper question edit it

3. 0,3,6,9

4. not proper I cannot understand.

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