Ch 1 Discrete Test Review

Is this a valid Social Security Number?

521-00-0034

Scheme: A four-digit ID number created so that $$d_4$$ (the check digit) makes the sum divisible by 6.

Which ID number is INVALID under the scheme?

Scheme: A four-digit ID number created so that $$d_4$$ ​ (the check digit) makes the sum divisible by 6.

Which digit(s) could be used to make 438? valid?

The check digit $$d_5$$ is selected to make the following weighted sum divisible by 5.

$$2d_1+5d_2+6d_3+4d_4$$

Find the check digit for ID #3815.

$$189\equiv17\left(mod\ 4\right)$$

$$54\equiv7\left(mod\ 11\right)$$

$$541\equiv2136\left(mod\ 5\right)$$

Explain why 16 | 48 is a true statement.

236 mod 6 = ?

Find the check digit $$d_7$$ using a mod 11 scheme.

738461