Đề-ca-mét vuông. Héc-tô-mét vuông
<p style="text-align: justify;">Để đo diện tích người ta còn dùng những đơn vị: <em>đề-ca-mét vuông, héc-tô-mét vuông</em>.</p> <h3 style="text-align: justify;" id="a-de-ca-meacutet-vuocircng">a) Đề-ca-mét vuông</h3> <p style="text-align: justify;">&nbsp;</p> <p><img style="display: block; margin-left: auto; margin-right: auto;" src="/uploads/tinymce/a-1665866129.PNG.webp" width="304" height="257" alt="hinh-anh-de-ca-met-vuong-hec-to-met-vuong-1618-0" title="hinh-anh-de-ca-met-vuong-hec-to-met-vuong-1618-0" loading="lazy"></p><div> <div class="ads-horizontal-wrapped" style="height: auto !important; min-height: 0px !important;">
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</div><p></p> <p style="text-align: justify;">&nbsp;</p> <p style="text-align: justify;"><em>Đề-ca-mét vuông</em> là diện tích của hình vuông có cạnh dài 1dam. Đề-ca-mét vuông viết tắt là dam<sup>2</sup>.</p> <p style="text-align: justify;">Ta thấy hình vuông 1dam<sup>2</sup> gồm 100 hình vuông 1m<sup>2</sup>.</p> <p style="text-align: justify;">1dam<sup>2 </sup>= 100m<sup>2</sup></p> <h3 style="text-align: justify;" id="b-heacutec-tocirc-meacutet-vuocircng">b) Héc-tô-mét vuông</h3> <p><img style="display: block; margin-left: auto; margin-right: auto;" src="/uploads/tinymce/b-1665866233.PNG.webp" width="324" height="283" alt="hinh-anh-de-ca-met-vuong-hec-to-met-vuong-1618-1" title="hinh-anh-de-ca-met-vuong-hec-to-met-vuong-1618-1" loading="lazy"></p> <p style="text-align: justify;"><em>Hét-tô-mét vuông</em>&nbsp;là diện tích của hình vuông có cạnh dài 1hm. Hét-tô-mét vuông viết tắt là hm<sup>2</sup>.</p> <p style="text-align: justify;">Ta thấy hình vuông 1hm<sup>2</sup>&nbsp;gồm 100 hình vuông 1dam<sup>2</sup>.</p> <p style="text-align: justify;">1hm<sup>2&nbsp;</sup>= 100dam<sup>2</sup></p> <h3 id="bagravei-tap">Bài tập</h3> <p><strong>1.</strong>Đọc các số đo diện tích: 105dam<sup>2</sup>;&nbsp; &nbsp; &nbsp; 32 600dam<sup>2</sup>;&nbsp; &nbsp; &nbsp;&nbsp;492hm<sup>2</sup>;&nbsp; &nbsp; &nbsp;&nbsp;180 350hm<sup>2</sup>.</p> <p style="text-align: justify;"><strong>2.</strong>Viết các số đo diện tích:</p> <p style="text-align: justify;">a) Hai trăm bảy mươi mốt đề-ca-mét vuông.</p> <p style="text-align: justify;">b) Mười tám nghìn chín trăm năm mươi tư đề-ca-mét vuông.</p> <p style="text-align: justify;">c) Sáu trăm linh ba héc-tô-mét vuông.</p> <p style="text-align: justify;">d) Ba mươi tư nghìn sáu trăm hai mươi héc-tô-mét vuông.</p> <p style="text-align: justify;"><strong>3.</strong>a) Viết số thích hợp vào chỗ chấm:</p> <p style="text-align: justify;">2dam<sup>2</sup> =... m<sup>2</sup><span style="font-size: 13.3333px;">&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; </span>3dam<sup>2</sup>15m<sup>2</sup>&nbsp;= ... m<sup>2</sup><span style="font-size: 13.3333px;">&nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; </span>200m<sup>2</sup>&nbsp;=... dam<sup>2</sup></p> <p style="text-align: justify;">30hm<sup>2</sup> =... dam<sup>2</sup><span style="font-size: 13.3333px;">&nbsp; &nbsp; &nbsp; &nbsp;</span>12hm<sup>2</sup> 5dam<sup>2</sup> = ... dam<sup>2&nbsp; &nbsp;</sup>760m<sup>2</sup> = ... dam<sup>2</sup>... m<sup>2</sup></p> <p style="text-align: justify;">b) Viết phân số thích vào chỗ chấm:</p> <p style="text-align: justify;">1m<sup>2</sup> =... dam<sup>2</sup>&nbsp; &nbsp; &nbsp; &nbsp;1dam<sup>2</sup>&nbsp;=... hm<sup>2</sup></p> <p style="text-align: justify;">3m<sup>2</sup> = ... dam<sup>2</sup><span style="font-size: 13.3333px;">&nbsp; &nbsp; &nbsp; &nbsp;</span>8dam<sup>2</sup>&nbsp;= ... hm<sup>2</sup>&nbsp;&nbsp;</p> <p style="text-align: justify;">27m<sup>2</sup>=... dam<sup>2</sup><span style="font-size: 13.3333px;">&nbsp; &nbsp; &nbsp; </span>15dam<sup>2</sup> =... hm<sup>2</sup></p> <p style="text-align: justify;">Hướng dẫn:</p> <p style="text-align: justify;">100m<sup>2</sup> = 1dam<sup>2</sup></p> <p style="text-align: justify;">1 m<sup>2</sup> = <mjx-container class="MathJax CtxtMenu_Attached_0" jax="CHTML" tabindex="0" ctxtmenu_counter="0" style="font-size: 116.7%; position: relative;"><mjx-math class="MJX-TEX" aria-hidden="true"><mjx-mfrac><mjx-frac><mjx-num><mjx-nstrut></mjx-nstrut><mjx-mn class="mjx-n" size="s"><mjx-c class="mjx-c31"></mjx-c></mjx-mn></mjx-num><mjx-dbox><mjx-dtable><mjx-line></mjx-line><mjx-row><mjx-den><mjx-dstrut></mjx-dstrut><mjx-mn class="mjx-n" size="s"><mjx-c class="mjx-c31"></mjx-c><mjx-c class="mjx-c30"></mjx-c><mjx-c class="mjx-c30"></mjx-c></mjx-mn></mjx-den></mjx-row></mjx-dtable></mjx-dbox></mjx-frac></mjx-mfrac></mjx-math><mjx-assistive-mml unselectable="on" display="inline"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>1</mn><mn>100</mn></mfrac></math></mjx-assistive-mml></mjx-container>dam<sup>2</sup></p> <p style="text-align: justify;">3m<sup>2</sup> = <mjx-container class="MathJax CtxtMenu_Attached_0" jax="CHTML" tabindex="0" ctxtmenu_counter="1" style="font-size: 116.7%; position: relative;"><mjx-math class="MJX-TEX" aria-hidden="true"><mjx-mfrac><mjx-frac><mjx-num><mjx-nstrut></mjx-nstrut><mjx-mn class="mjx-n" size="s"><mjx-c class="mjx-c33"></mjx-c></mjx-mn></mjx-num><mjx-dbox><mjx-dtable><mjx-line></mjx-line><mjx-row><mjx-den><mjx-dstrut></mjx-dstrut><mjx-mn class="mjx-n" size="s"><mjx-c class="mjx-c31"></mjx-c><mjx-c class="mjx-c30"></mjx-c><mjx-c class="mjx-c30"></mjx-c></mjx-mn></mjx-den></mjx-row></mjx-dtable></mjx-dbox></mjx-frac></mjx-mfrac></mjx-math><mjx-assistive-mml unselectable="on" display="inline"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>3</mn><mn>100</mn></mfrac></math></mjx-assistive-mml></mjx-container>dam<sup>2</sup></p> <p style="text-align: justify;"><strong>4.</strong>Viết các số đo sau dưới dạng số đo có đơn vị là đề-ca-mét vuông (theo mẫu):</p> <p style="text-align: justify;">5dam<sup>2</sup>23m<sup>2</sup> ;&nbsp; &nbsp; &nbsp; 16dam<sup>2</sup>91m<sup>2</sup> ; &nbsp; &nbsp; &nbsp;32dam<sup>2</sup>5m<sup>2</sup>.</p> <p style="text-align: justify;">Mẫu:&nbsp; 5dam<sup>2</sup> 23m<sup>2</sup> = 5dam<sup>2</sup> + <mjx-container class="MathJax CtxtMenu_Attached_0" jax="CHTML" tabindex="0" ctxtmenu_counter="2" style="font-size: 116.7%; position: relative;"><mjx-math class="MJX-TEX" aria-hidden="true"><mjx-mfrac><mjx-frac><mjx-num><mjx-nstrut></mjx-nstrut><mjx-mn class="mjx-n" size="s"><mjx-c class="mjx-c32"></mjx-c><mjx-c class="mjx-c33"></mjx-c></mjx-mn></mjx-num><mjx-dbox><mjx-dtable><mjx-line></mjx-line><mjx-row><mjx-den><mjx-dstrut></mjx-dstrut><mjx-mn class="mjx-n" size="s"><mjx-c class="mjx-c31"></mjx-c><mjx-c class="mjx-c30"></mjx-c><mjx-c class="mjx-c30"></mjx-c></mjx-mn></mjx-den></mjx-row></mjx-dtable></mjx-dbox></mjx-frac></mjx-mfrac></mjx-math><mjx-assistive-mml unselectable="on" display="inline"><math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mn>23</mn><mn>100</mn></mfrac></math></mjx-assistive-mml></mjx-container>dam<sup>2</sup> = <mjx-container class="MathJax CtxtMenu_Attached_0" jax="CHTML" tabindex="0" ctxtmenu_counter="3" style="font-size: 116.7%; position: relative;"><mjx-math class="MJX-TEX" aria-hidden="true"><mjx-mn class="mjx-n"><mjx-c class="mjx-c35"></mjx-c></mjx-mn><mjx-mfrac><mjx-frac><mjx-num><mjx-nstrut></mjx-nstrut><mjx-mn class="mjx-n" size="s"><mjx-c class="mjx-c32"></mjx-c><mjx-c class="mjx-c33"></mjx-c></mjx-mn></mjx-num><mjx-dbox><mjx-dtable><mjx-line></mjx-line><mjx-row><mjx-den><mjx-dstrut></mjx-dstrut><mjx-mn class="mjx-n" size="s"><mjx-c class="mjx-c31"></mjx-c><mjx-c class="mjx-c30"></mjx-c><mjx-c class="mjx-c30"></mjx-c></mjx-mn></mjx-den></mjx-row></mjx-dtable></mjx-dbox></mjx-frac></mjx-mfrac></mjx-math><mjx-assistive-mml unselectable="on" display="inline"><math xmlns="http://www.w3.org/1998/Math/MathML"><mn>5</mn><mfrac><mn>23</mn><mn>100</mn></mfrac></math></mjx-assistive-mml></mjx-container>dam<sup>2</sup></p> <p style="text-align: justify;">&nbsp;</p>