Page No 260:
Question 1:
If 21y5 is a multiple of 9, where y is a digit, what is the value of y?
Page No 260:
Question 2:
If 31z5 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?
Page No 260:
Question 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)
Page No 260:
Question 4:
If 31z5 is a multiple of 3, where z is a digit, what might be the values of z?
