What is the tens digit of the positive integer r ?
(1) The tens digit of <span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML" tabindex="0" data-mathml="r10" role="presentation" style="box-sizing: border-box; display: inline-block; line-height: 0; font-size: 24.2px; word-wrap: normal; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding-top: 1px; padding-bottom: 1px; position: relative;">r10r10 is 3.
(2) The hundreds digit of 10r is 6.