小学五年级数学题，出一个生动的教学讲解视频---**Extracted Content:** **Question 3:** 有若干块长 60 cm、宽 40 cm 的木板, 把这些木板平铺在地上, 至少要用多少块这样的木板才能铺成一个正方形? **Handwritten Calculations:** 20 | 60 / 3 40 / 2 [60, 40] = 20 x 3 x 2 = 120 cm 120 ÷ 60 = 2 (块) 120 ÷ 40 = 3 (块) 2 x 3 = 6 (块). **Diagram Description:** * **Type:** Geometric diagram composed of rectangles. * **Main Elements:** * The diagram shows a shape made of connected rectangles. * Solid lines define the outer boundary and some internal boundaries. * Dashed lines indicate internal divisions within the shape, suggesting three vertical rectangular sections. * Two dimensions are labeled with arrows: 'l' is a horizontal dimension representing the total width, and 'd' is a vertical dimension representing the height of a part of the shape. * The shape appears to be composed of a large rectangle on the left connected to a smaller rectangle on the right, with dashed lines dividing the larger rectangle into three vertical sections. Alternatively, it could represent the net of a 3D shape. * **Labels and Annotations:** The dimensions are labeled 'l' and 'd'.