Page 49 - Maths Class 05

3. For representing 3 + 4, paste one strip of length 3

units and then paste another strip of length 4 units
in the same line on the grid paper whithout leaving
any gap Fig. 1(c).
Fig 1(c)
4. For representing 4 + 3, paste one strip of length 4
units and then paste another strip of length 3 units

in the same line on the same grid paper without
leaving any gap Fig. 1(d)

5. Now, compare (by counting number of boxes) the
length of strips obtained in Step 3 and Step 4. Fig 1(d)
Are they equal ?

6. Repeat the activity for some more pairs of whole numbers and write your result.
Observations :

Number of shade boxes in the presentation of 3 + 4 = ___________
Number of shade boxes in the presentation of 4 + 3 = ___________

Thus, 3 + 4 = 4 + 3

Hence, addition is commutative for whole numbers.
Procedure (b) : To verify 3 × 4 = 4 × 3

1 Cutout three strips each of 4 boxes from a grid paper and
shade them with any colour (Say blue).

2. Place them on a grid paper to form a rectangle as shown in Fig 1(e)
Fig. 1(e)
3. Now, cutout four strips each of length 3 units from the gird
paper. Colour them (say Red) and place them on the same

grid paper to form a rectangle as shown in Fig. 1(f)
4. Now, compare the number of boxes in each of the two
rectangles obtained. Are they equal ?

5. Repeat the activity for some more pairs of whole numbers
and write your result.

Observations : Fig 1(f)
Number of shaded boxes in the representation of 3 × 4 = ___________

Number of shaded boxes in the representation of 4 × 3 = ___________
Thus, 3 × 4 = 4 × 3

Hence, multiplication is commutative for whole numbers.

Mathematics-5 49