Mathematics Magazine for Grades 1-12  

Grade 3

Theory: 

Inverse Relationship between Multiplication and Division

There is an inverse relationship between multiplication and division just like there was between addition and subtraction.

The equation 3  7 = 21 has the inverse relationships:
21 ÷ 3 = 7
21 ÷ 7 = 3

Similar relationships exist for division. The equation 45 ÷ 5 = 9 has the inverse relationships:
5  9 = 45
9  5 = 45

Solutions from the Previous Issue:

Verify if the following equalities are true:

1.        766 – ( 138  3 – 428 2) = 789 – 138  2

        Solution: 766 – ( 138  3 – 428 2) = 766 – (414 – 214) = 766 – 200 = 566

        789 – 138  2 = 789 – 276 = 513

         The equality 766 – ( 138  3 – 428 2) = 789 – 138  2 is false

2.        366 – (627 3 –387 3) +125 = 229 + 3 128

        Solution: 366 – (627 3 –387 3) + 125 = 366 – (209 – 129) + 125 =

366 – 80 + 125 = 411

        229 + 3 128 = 229 + 384 = 613

        The initial equality is false

3.        Calculate a + b + c knowing that 165 – 9  a = 8  b = 30  c = 120

        Solution: 30  c = 120                c = 4      

8  b = 120                                   b = 15

165 – 9  a = 120         165 -120 – 9  a = 120 – 120               45 = 9  a

                                                        a = 5

Proposed Exercises:

Complete the following table:

Read more on the written version of the publication.