Using the meaning of multiplication and division, can you explain why multiplying by 5 Class 7

Using the meaning of multiplication and division, can you explain why multiplying by 5 Class 7

Question 1.

Using the meaning of multiplication and division, can you explain why multiplying by 5 is the same as dividing by 2 and multiplying by 10? Class 7

Solution:

Because 10 ÷ 2 = 5

Question 2.

Find quick ways to calculate these products: Class 7

(a) 2 × 1768 × 50

Solution:

2 × 1768 × 50 = 2 × 1768 × [latex]\frac{100}{2}[/latex]

= 176800

(b) 72 × 125 [Hint: 125 = [latex]\frac{1000}{8}[/latex]]

Solution:

72 × 125 = 72 × [latex]\frac{1000}{8}[/latex]

= 9 × 1000 = 9000

(c) 125 × 40 × 8 × 25

Solution:

= [latex]\frac{1000}{8}[/latex] × 40 × 8 × [latex]\frac{100}{4}[/latex]

= 1000 × 10 × 100

= 1000000

Question 3.

Calculate these products quickly. Class 7

(a) 25 × 12 = _____________

Solution:

25 × 12 = [latex]\frac{100}{4}[/latex] × 4 × 3 = 300

(b) 25 × 240 = ____________

Solution:

25 × 240 = [latex]\frac{100}{4}[/latex] × 4 × 60 = 6000

(c) 250 × 120 = ____________

Solution:

250 × 120 = [latex]\frac{1000}{4}[/latex] × 4 × 30 = 30000

(d) 2500 × 12 = ____________

Solution:

25 × 240 = [latex]\frac{10000}{4}[/latex] × 3 × 4 = 30000

(e) ________ × __________ = 120000000

Solution:

12 × 10000000 = 120000000 or 50 × 2400000 and so on.