How many 4-digit numbers are there with no digit repeated?

[email_link] ]]>If **U _{1}**,

- U1 + U2
- U1U2
- U1
^{2} - U1 + L1
- U1L1
- L1 + L2

What is the probability that six randomly chosen positive integers are relatively prime ?

[email_link] ]]>Two women start walking at the sunrise, one from point A to B and another from point B to A. The pass each other exactly at noon. The first woman reaches point B at 4PM and the second reaches point A at 9PM.

At what time did sun rise that day?

[email_link] ]]>