Hi,
Text is actually stored/represented by numbers within Excel, that's why there are functions you can use to include/exclude certain values, see examples below:
Someone else here may be able to explain this to you in more detail.
<b>Excel 2010</b><table cellpadding="2.5px" rules="all" style=";background-color: rgb(255,255,255);border: 1px solid;border-collapse: collapse; border-color: rgb(187,187,187)"><colgroup><col width="25px" style="background-color: rgb(218,231,245)" /><col /><col /><col /><col /></colgroup><thead><tr style=" background-color: rgb(218,231,245);text-align: center;color: rgb(22,17,32)"><th></th><th>A</th><th>B</th><th>C</th><th>D</th></tr></thead><tbody><tr ><td style="color: rgb(22,17,32);text-align: center;">1</td><td style=";">text</td><td style="text-align: right;;">TRUE</td><td style="text-align: right;;">FALSE</td><td style="text-align: right;;">TRUE</td></tr><tr ><td style="color: rgb(22,17,32);text-align: center;">2</td><td style="text-align: right;;">123</td><td style="text-align: right;;">TRUE</td><td style="text-align: right;;">TRUE</td><td style="text-align: right;;">FALSE</td></tr></tbody></table><p style="width:4.8em;font-weight:bold;margin:0;padding:0.2em 0.6em 0.2em 0.5em;border: 1px solid rgb(187,187,187);border-top:none;text-align: center;background-color: rgb(218,231,245);color: rgb(22,17,32)">Sheet1</p><br /><br /><table width="85%" cellpadding="2.5px" rules="all" style=";border: 2px solid black;border-collapse:collapse;padding: 0.4em;background-color: rgb(255,255,255)" ><tr><td style="padding:6px" ><b>Worksheet Formulas</b><table cellpadding="2.5px" width="100%" rules="all" style="border: 1px solid;text-align:center;background-color: rgb(255,255,255);border-collapse: collapse; border-color: rgb(187,187,187)"><thead><tr style=" background-color: rgb(218,231,245);color: rgb(22,17,32)"><th width="10px">Cell</th><th style="text-align:left;padding-left:5px;">Formula</th></tr></thead><tbody><tr><th width="10px" style=" background-color: rgb(218,231,245);color: rgb(22,17,32)">B1</th><td style="text-align:left">=A1>0</td></tr><tr><th width="10px" style=" background-color: rgb(218,231,245);color: rgb(22,17,32)">C1</th><td style="text-align:left">=ISNUMBER(<font color="Blue">A1</font>)</td></tr><tr><th width="10px" style=" background-color: rgb(218,231,245);color: rgb(22,17,32)">D1</th><td style="text-align:left">=ISTEXT(<font color="Blue">A1</font>)</td></tr><tr><th width="10px" style=" background-color: rgb(218,231,245);color: rgb(22,17,32)">B2</th><td style="text-align:left">=A2>0</td></tr><tr><th width="10px" style=" background-color: rgb(218,231,245);color: rgb(22,17,32)">C2</th><td style="text-align:left">=ISNUMBER(<font color="Blue">A2</font>)</td></tr><tr><th width="10px" style=" background-color: rgb(218,231,245);color: rgb(22,17,32)">D2</th><td style="text-align:left">=ISTEXT(<font color="Blue">A2</font>)</td></tr></tbody></table></td></tr></table><br />